Vulnerability-Lookup

CVE-2026-100349 (GCVE-0-2026-100349)

Vulnerability from cvelistv5 – Published: 2026-10-15 15:50 – Updated: 2026-10-16 17:13

Title

kin-openapi openapi3filter: nil-pointer panic in ValidateResponse on a response header declared with content

Summary

kin-openapi is a Go project for handling OpenAPI files. Prior to 0.146.0, openapi3filter.ValidateResponse passes a nil response header schema to decodeValue when an OpenAPI document declares the header with content instead of schema. The document passes validation, but every response validation for the affected operation dereferences the nil schema and panics even when the response does not contain the declared header. Applications that ingest an untrusted specification can expose this as remote availability impact, while applications using only trusted local specifications still crash when the affected operation is exercised. This issue is fixed in version 0.146.0.

Severity

8.2 (High)


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

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-10-15 20:24 UTC

CWE

CWE-476 - NULL Pointer Dereference

Assigner

GitHub_M CNA under the mitre root

CNA scorecard C 72/100 over 7771 records in the last 180 days details

References

3 references

URL	Tags
https://github.com/getkin/kin-openapi/security/ad…	x_refsource_CONFIRM
https://github.com/getkin/kin-openapi/commit/f544…	x_refsource_MISC
https://github.com/getkin/kin-openapi/releases/ta…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version	CPE status
getkin	kin-openapi	Affected: < 0.146.0	guessed

Show details on NVD website

JSON

To clipboard

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}

FKIE_CVE-2026-100349

Vulnerability from fkie_nvd - Published: 2026-10-15 16:17 - Updated: 2026-10-16 18:17

Severity

8.2 (High) - CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/getkin/kin-openapi/commit/f5441d67f855ed34d975b3b85665764644ab1459
	security-advisories@github.com	https://github.com/getkin/kin-openapi/releases/tag/v0.146.0
	security-advisories@github.com	https://github.com/getkin/kin-openapi/security/advisories/GHSA-74vm-87hj-r66f

Impacted products

	Vendor	Product	Version

JSON

To clipboard

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}

GHSA-74VM-87HJ-R66F

Vulnerability from github – Published: 2026-10-16 19:58 – Updated: 2026-10-16 19:58

Summary

kin-openapi openapi3filter: nil-pointer panic in ValidateResponse on a response header declared with content

Details

Summary

ValidateResponse panics on a nil pointer when a spec declares a response header with content instead of schema. doc.Validate() accepts that document, so the crash comes from a spec the library just called valid.

Same class as GHSA-jpcw-4wr7-c3vq, which covered the request-parameter case in v0.144.0; this is the response-header path.

Affects github.com/getkin/kin-openapi <= v0.145.0. Reproduced on master 947498e5a6bd, Go 1.26.

Details

A content-typed response header has headerRef.Value.Schema == nil.

validate_response.go:181 passes it straight through:

if decodedValue, found, err = decodeValue(dec, headerName, sm, headerRef.Value.Schema, headerRef.Value.Required); err != nil {

and req_resp_decoder.go:273 is where it lands:

if len(schema.Value.AllOf) > 0 {

Two things I checked rather than assumed. The response does not need to carry the header; declaring it is enough, and then every call for that operation panics. And the body path is fine, :114 returns early on a nil schema, so this is headers only. The PoC keeps the body case as a control.

PoC

Drop into openapi3filter/ and run:

go test ./openapi3filter/ -run NilSchema -v

package openapi3filter_test

import (
    "context"
    "io"
    "net/http"
    "net/http/httptest"
    "strings"
    "testing"

    "github.com/getkin/kin-openapi/openapi3"
    "github.com/getkin/kin-openapi/openapi3filter"
    "github.com/getkin/kin-openapi/routers"
)

const specBody = `
openapi: 3.0.3
info: {title: poc, version: "1.0.0"}
paths:
  /x:
    get:
      responses:
        "200":
          description: ok
          content:
            application/json: {}
`

const specHeader = `
openapi: 3.0.3
info: {title: poc, version: "1.0.0"}
paths:
  /x:
    get:
      responses:
        "200":
          description: ok
          headers:
            X-Thing:
              content:
                application/json: {}
`

func validatedInput(t *testing.T, spec string, hdr http.Header) *openapi3filter.ResponseValidationInput {
    t.Helper()
    doc, err := openapi3.NewLoader().LoadFromData([]byte(spec))
    if err != nil {
        t.Fatalf("load: %v", err)
    }
    if err := doc.Validate(context.Background()); err != nil {
        t.Fatalf("doc.Validate rejected the spec, so this repro proves nothing: %v", err)
    }
    op := doc.Paths.Find("/x").Get
    req := httptest.NewRequest(http.MethodGet, "/x", nil)
    return &openapi3filter.ResponseValidationInput{
        RequestValidationInput: &openapi3filter.RequestValidationInput{
            Request: req,
            Route:   &routers.Route{Spec: doc, Operation: op, Method: http.MethodGet, Path: "/x"},
        },
        Status: 200,
        Header: hdr,
        Body:   io.NopCloser(strings.NewReader(`{}`)),
    }
}

// Control: body path returns early on a nil schema.
func TestControl_ResponseBodyNilSchema(t *testing.T) {
    in := validatedInput(t, specBody, http.Header{"Content-Type": {"application/json"}})
    defer func() {
        if r := recover(); r != nil {
            t.Errorf("body path panicked, expected clean return: %v", r)
        }
    }()
    if err := openapi3filter.ValidateResponse(context.Background(), in); err != nil {
        t.Errorf("body path returned %v, expected nil", err)
    }
}

// The response does not carry X-Thing. Declaring the header is enough.
func TestResponseHeaderNilSchema(t *testing.T) {
    in := validatedInput(t, specHeader, http.Header{"Content-Type": {"application/json"}})
    if err := openapi3filter.ValidateResponse(context.Background(), in); err != nil {
        t.Fatalf("no panic; got err = %v (already fixed?)", err)
    }
}

Output:

=== RUN   TestControl_ResponseBodyNilSchema
--- PASS: TestControl_ResponseBodyNilSchema (0.00s)
=== RUN   TestResponseHeaderNilSchema
--- FAIL: TestResponseHeaderNilSchema (0.00s)
panic: runtime error: invalid memory address or nil pointer dereference [recovered, repanicked]
[signal SIGSEGV: segmentation violation code=0x1 addr=0x20 pc=0x7f6d2a]

github.com/getkin/kin-openapi/openapi3filter.decodeValue(...)
    /src/openapi3filter/req_resp_decoder.go:273 +0x4a
github.com/getkin/kin-openapi/openapi3filter.validateResponseHeader(...)
    /src/openapi3filter/validate_response.go:181 +0x146
github.com/getkin/kin-openapi/openapi3filter.ValidateResponse(...)
    /src/openapi3filter/validate_response.go:89 +0xafa

The FAIL is the point: control passes, the header case takes the binary down.

Ran in a container against a fresh clone of master. I have not tried it against a live proxy.

Impact

A process crash instead of an error return. Declaring the header is enough, so it is every call on that operation rather than an occasional one.

If the spec comes from somewhere else -- gateways, linters, anything ingesting specs it did not write -- that is a trust boundary, and it becomes remote availability.

If it is your own spec, nothing attacker-controlled starts it, but any client reaching that route then crashes the process. It fires on every call, so normally you would see it the first time that route runs. A spec edited without exercising the route is the case where you would not. That is the difference from GHSA-jpcw, where the attacker supplied the trigger. I have left severity unset; the two cases do not score the same.

On how common it is, I checked rather than guessed. Of roughly 1,500 OpenAPI 3.x specs on apis.guru, one declares content-typed response headers -- VTEX Catalog API -- and not in one corner of it: the shape repeats across its operations, so for that consumer this is not an edge case.

The header names in it (X-AspNet-Version, p3p, a few malformed ones) look like a generator emitting content where it could not infer a schema, and apis.guru only indexes public specs. There is no content-typed response header in this repo's testdata either.

Workarounds

Use schema on the response header, or skip ValidateResponse for those operations. ExcludeResponseBody will not do it -- headers are validated before that check.

Suggested fix

Nil-guard at the top of decodeValue:

if schema == nil {
    return nil, false, nil
}

Returning nil leaves a content-typed header unvalidated rather than erroring, so it trades the crash for a silent gap. An error return kills the panic just as well if you would rather it surfaced.

Severity

8.2 (High)


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

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{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 0.145.0"
      },
      "package": {
        "ecosystem": "Go",
        "name": "github.com/getkin/kin-openapi"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.146.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-100349"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-476"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-10-16T19:58:46Z",
    "nvd_published_at": "2026-10-15T16:17:30Z",
    "severity": "HIGH"
  },
  "details": "## Summary\n\n`ValidateResponse` panics on a nil pointer when a spec declares a response header with `content` instead of `schema`. `doc.Validate()` accepts that document, so the crash comes from a spec the library just called valid.\n\nSame class as GHSA-jpcw-4wr7-c3vq, which covered the request-parameter case in v0.144.0; this is the response-header path.\n\nAffects `github.com/getkin/kin-openapi` `\u003c= v0.145.0`. Reproduced on master `947498e5a6bd`, Go 1.26.\n\n## Details\n\nA `content`-typed response header has `headerRef.Value.Schema == nil`.\n\n`validate_response.go:181` passes it straight through:\n\n```go\nif decodedValue, found, err = decodeValue(dec, headerName, sm, headerRef.Value.Schema, headerRef.Value.Required); err != nil {\n```\n\nand `req_resp_decoder.go:273` is where it lands:\n\n```go\nif len(schema.Value.AllOf) \u003e 0 {\n```\n\nTwo things I checked rather than assumed. The response does not need to carry the header; declaring it is enough, and then every call for that operation panics. And the body path is fine, `:114` returns early on a nil schema, so this is headers only. The PoC keeps the body case as a control.\n\n## PoC\n\nDrop into `openapi3filter/` and run:\n\n```\ngo test ./openapi3filter/ -run NilSchema -v\n```\n\n```go\npackage openapi3filter_test\n\nimport (\n\t\"context\"\n\t\"io\"\n\t\"net/http\"\n\t\"net/http/httptest\"\n\t\"strings\"\n\t\"testing\"\n\n\t\"github.com/getkin/kin-openapi/openapi3\"\n\t\"github.com/getkin/kin-openapi/openapi3filter\"\n\t\"github.com/getkin/kin-openapi/routers\"\n)\n\nconst specBody = `\nopenapi: 3.0.3\ninfo: {title: poc, version: \"1.0.0\"}\npaths:\n  /x:\n    get:\n      responses:\n        \"200\":\n          description: ok\n          content:\n            application/json: {}\n`\n\nconst specHeader = `\nopenapi: 3.0.3\ninfo: {title: poc, version: \"1.0.0\"}\npaths:\n  /x:\n    get:\n      responses:\n        \"200\":\n          description: ok\n          headers:\n            X-Thing:\n              content:\n                application/json: {}\n`\n\nfunc validatedInput(t *testing.T, spec string, hdr http.Header) *openapi3filter.ResponseValidationInput {\n\tt.Helper()\n\tdoc, err := openapi3.NewLoader().LoadFromData([]byte(spec))\n\tif err != nil {\n\t\tt.Fatalf(\"load: %v\", err)\n\t}\n\tif err := doc.Validate(context.Background()); err != nil {\n\t\tt.Fatalf(\"doc.Validate rejected the spec, so this repro proves nothing: %v\", err)\n\t}\n\top := doc.Paths.Find(\"/x\").Get\n\treq := httptest.NewRequest(http.MethodGet, \"/x\", nil)\n\treturn \u0026openapi3filter.ResponseValidationInput{\n\t\tRequestValidationInput: \u0026openapi3filter.RequestValidationInput{\n\t\t\tRequest: req,\n\t\t\tRoute:   \u0026routers.Route{Spec: doc, Operation: op, Method: http.MethodGet, Path: \"/x\"},\n\t\t},\n\t\tStatus: 200,\n\t\tHeader: hdr,\n\t\tBody:   io.NopCloser(strings.NewReader(`{}`)),\n\t}\n}\n\n// Control: body path returns early on a nil schema.\nfunc TestControl_ResponseBodyNilSchema(t *testing.T) {\n\tin := validatedInput(t, specBody, http.Header{\"Content-Type\": {\"application/json\"}})\n\tdefer func() {\n\t\tif r := recover(); r != nil {\n\t\t\tt.Errorf(\"body path panicked, expected clean return: %v\", r)\n\t\t}\n\t}()\n\tif err := openapi3filter.ValidateResponse(context.Background(), in); err != nil {\n\t\tt.Errorf(\"body path returned %v, expected nil\", err)\n\t}\n}\n\n// The response does not carry X-Thing. Declaring the header is enough.\nfunc TestResponseHeaderNilSchema(t *testing.T) {\n\tin := validatedInput(t, specHeader, http.Header{\"Content-Type\": {\"application/json\"}})\n\tif err := openapi3filter.ValidateResponse(context.Background(), in); err != nil {\n\t\tt.Fatalf(\"no panic; got err = %v (already fixed?)\", err)\n\t}\n}\n```\n\nOutput:\n\n```\n=== RUN   TestControl_ResponseBodyNilSchema\n--- PASS: TestControl_ResponseBodyNilSchema (0.00s)\n=== RUN   TestResponseHeaderNilSchema\n--- FAIL: TestResponseHeaderNilSchema (0.00s)\npanic: runtime error: invalid memory address or nil pointer dereference [recovered, repanicked]\n[signal SIGSEGV: segmentation violation code=0x1 addr=0x20 pc=0x7f6d2a]\n\ngithub.com/getkin/kin-openapi/openapi3filter.decodeValue(...)\n\t/src/openapi3filter/req_resp_decoder.go:273 +0x4a\ngithub.com/getkin/kin-openapi/openapi3filter.validateResponseHeader(...)\n\t/src/openapi3filter/validate_response.go:181 +0x146\ngithub.com/getkin/kin-openapi/openapi3filter.ValidateResponse(...)\n\t/src/openapi3filter/validate_response.go:89 +0xafa\n```\n\nThe `FAIL` is the point: control passes, the header case takes the binary down.\n\nRan in a container against a fresh clone of master. I have not tried it against a live proxy.\n\n## Impact\n\nA process crash instead of an error return. Declaring the header is enough, so it is every call on that operation rather than an occasional one.\n\nIf the spec comes from somewhere else -- gateways, linters, anything ingesting specs it did not write -- that is a trust boundary, and it becomes remote availability.\n\nIf it is your own spec, nothing attacker-controlled starts it, but any client reaching that route then crashes the process. It fires on every call, so normally you would see it the first time that route runs. A spec edited without exercising the route is the case where you would not. That is the difference from GHSA-jpcw, where the attacker supplied the trigger. I have left severity unset; the two cases do not score the same.\n\nOn how common it is, I checked rather than guessed. Of roughly 1,500 OpenAPI 3.x specs on apis.guru, one declares content-typed response headers -- VTEX Catalog API -- and not in one corner of it: the shape repeats across its operations, so for that consumer this is not an edge case.\n\nThe header names in it (`X-AspNet-Version`, `p3p`, a few malformed ones) look like a generator emitting `content` where it could not infer a schema, and apis.guru only indexes public specs. There is no content-typed response header in this repo\u0027s testdata either.\n\n## Workarounds\n\nUse `schema` on the response header, or skip `ValidateResponse` for those operations. `ExcludeResponseBody` will not do it -- headers are validated before that check.\n\n## Suggested fix\n\nNil-guard at the top of `decodeValue`:\n\n```go\nif schema == nil {\n\treturn nil, false, nil\n}\n```\n\nReturning nil leaves a `content`-typed header unvalidated rather than erroring, so it trades the crash for a silent gap. An error return kills the panic just as well if you would rather it surfaced.",
  "id": "GHSA-74vm-87hj-r66f",
  "modified": "2026-10-16T19:58:46Z",
  "published": "2026-10-16T19:58:46Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/getkin/kin-openapi/security/advisories/GHSA-74vm-87hj-r66f"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-100349"
    },
    {
      "type": "WEB",
      "url": "https://github.com/getkin/kin-openapi/commit/f5441d67f855ed34d975b3b85665764644ab1459"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/getkin/kin-openapi"
    },
    {
      "type": "WEB",
      "url": "https://github.com/getkin/kin-openapi/releases/tag/v0.146.0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "kin-openapi openapi3filter: nil-pointer panic in ValidateResponse on a response header declared with content"
}

RHSA-2026:76677

Vulnerability from csaf_redhat - Published: 2026-10-06 08:26 - Updated: 2026-10-16 23:04

Summary

Red Hat Security Advisory: Red Hat Hardened Images RPMs bug fix and enhancement update

Severity

Important

Scope

9 vulnerabilities in this advisory, including CVE-2026-100349.

CVE-2026-100349

A flaw was found in kin-openapi. This vulnerability allows an attacker to cause a Denial of Service (DoS) by triggering an application crash during response validation. When an OpenAPI specification declares a response header using content rather than a schema, the validation logic attempts to dereference an uninitialized pointer, causing the application to panic and terminate.

7.5 (High)


                
                  CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Fixed: 3 products

https://access.redhat.com/errata/RHSA-2026:76677

Open the full advisory

RHSA-2026:82637

Vulnerability from csaf_redhat - Published: 2026-10-14 00:21 - Updated: 2026-10-16 14:52

Summary

Red Hat Security Advisory: Red Hat Hardened Images RPMs bug fix and enhancement update

Severity

Important

Scope

5 vulnerabilities in this advisory, including CVE-2026-100349.

CVE-2026-100349

7.5 (High)


                
                  CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Fixed: 4 products

https://access.redhat.com/errata/RHSA-2026:82637

Open the full advisory

Sightings

Author	Source	Type	Date	Other

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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.

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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.
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CVE-2026-100349 (GCVE-0-2026-100349)

FKIE_CVE-2026-100349

GHSA-74VM-87HJ-R66F

Summary

Details

PoC

Impact

Workarounds

Suggested fix

RHSA-2026:76677

RHSA-2026:82637

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