Vulnerability-Lookup

GHSA-9F29-V6MM-PW6W

Vulnerability from github – Published: 2026-02-18 15:25 – Updated: 2026-02-19 21:56

Summary

opa-envoy-plugin has an Authorization Bypass via Double-Slash Path Misinterpretation in input.parsed_path

Details

A security vulnerability has been discovered in how the input.parsed_path field is constructed. HTTP request paths are treated as full URIs when parsed; interpreting leading path segments prefixed with double slashes (//) as authority components, and therefore dropping them from the parsed path. This creates a path interpretation mismatch between authorization policies and backend servers, enabling attackers to bypass access controls by crafting requests where the authorization filter evaluates a different path than the one ultimately served.

Attack example

HTTP request:

GET //admin/users HTTP/1.1
Host: example.com

Policy sees:

The leading //admin path segment is interpreted as an authority component, and dropped from input.parsed_path field:

{
  "parsed_path": ["users"]
}

Backend receives:

//admin/users path, normalized to /admin/users.

Affected Request Pattern Examples

Request path	`input.parsed_path`	`input.attributes.request.http.path`	Discrepancy
/	[""]	/	✅ None
//foo	[""]	//foo	❌ Mismatch
/admin	["admin"]	/admin	✅ None
/admin/users	["admin", "users"]	/admin/users	✅ None
//admin/users	["users"]	//admin/users	❌ Mismatch

Impact

Users are impacted if all the following conditions apply:

Protected resources are path-hierarchical (e.g., /admin/users vs /users)
Authorization policies use input.parsed_path for path-based decisions
Backend servers apply lenient path normalization

Patches

Go: v1.13.2-envoy-2 Docker: 1.13.2-envoy-2, 1.13.2-envoy-2-static

Workarounds

Users who cannot immediately upgrade opa-envoy-plugin are recommended to apply one, or more, of the workarrounds described below.

1. Enable the `merge_slashes` Envoy configuration option

As per Envoy best practices, enabling the merge_slashes configuration option in Envoy will remove redundant slashes from the request path before filtering is applied, effectively mitigating the input.parsed_path issue described in this advisory.

2. Use `input.attributes.request.http.path` instead of `input.parsed_path` in policies

The input.attributes.request.http.path field contains the unprocessed, raw request path. Users are recommended to update any policy using input.parsed_path to instead use the input.attributes.request.http.path field.

Example

package example

# Use instead of input.parsed_path
parsed_path := split(                                        # tokenize into array
    trim_left(                                               # drop leading slashes
        urlquery.decode(input.attributes.request.http.path), # url-decode the path
        "/",
    ),
    "/",
)

Severity

7.1 (High)


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

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 1.13.1-envoy"
      },
      "package": {
        "ecosystem": "Go",
        "name": "github.com/open-policy-agent/opa-envoy-plugin"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.13.2-envoy-2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-26205"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-863"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-02-18T15:25:04Z",
    "nvd_published_at": "2026-02-19T20:25:43Z",
    "severity": "HIGH"
  },
  "details": "A security vulnerability has been discovered in how the `input.parsed_path` field is constructed. HTTP request paths are treated as full URIs when parsed; interpreting leading path segments prefixed with double slashes (`//`) as [authority](https://datatracker.ietf.org/doc/html/rfc3986#section-3.2) components, and therefore dropping them from the parsed path. This creates a path interpretation mismatch between authorization policies and backend servers, enabling attackers to bypass access controls by crafting requests where the authorization filter evaluates a different path than the one ultimately served.\n\n#### Attack example\n\n**HTTP request:**\n\n```\nGET //admin/users HTTP/1.1\nHost: example.com\n```\n\n**Policy sees:**\n\nThe leading `//admin` path segment is interpreted as an authority component, and dropped from `input.parsed_path` field:\n\n\n```json\n{\n  \"parsed_path\": [\"users\"]\n}\n```\n\n**Backend receives:**\n\n`//admin/users` path, normalized to `/admin/users`.\n\n#### Affected Request Pattern Examples\n\n| Request path | `input.parsed_path` | `input.attributes.request.http.path` | Discrepancy |\n| - | - | - | - |\n| / | [\"\"] | / | \u2705 None |\n| //foo  | [\"\"] | //foo| \u274c Mismatch |\n| /admin | [\"admin\"] | /admin | \u2705 None |\n| /admin/users | [\"admin\", \"users\"] |  /admin/users | \u2705 None |\n| //admin/users  | [\"users\"] | //admin/users | \u274c Mismatch |\n\n### Impact\n\nUsers are impacted if all the following conditions apply:\n\n1. Protected resources are path-hierarchical (e.g., `/admin/users` vs `/users`)\n2. Authorization policies use `input.parsed_path` for path-based decisions\n3. Backend servers apply lenient path normalization\n\n### Patches\n\nGo: `v1.13.2-envoy-2`\nDocker: `1.13.2-envoy-2`, `1.13.2-envoy-2-static`\n\n### Workarounds\n\nUsers who cannot immediately upgrade opa-envoy-plugin are recommended to apply one, or more, of the workarrounds described below.\n\n#### 1. Enable the `merge_slashes` Envoy configuration option\n\nAs per [Envoy best practices](https://www.envoyproxy.io/docs/envoy/v1.37.0/configuration/best_practices/edge.html), enabling the [merge_slashes](https://www.envoyproxy.io/docs/envoy/latest/api-v3/extensions/filters/network/http_connection_manager/v3/http_connection_manager.proto#envoy-v3-api-field-extensions-filters-network-http-connection-manager-v3-httpconnectionmanager-merge-slashes) configuration option in Envoy will remove redundant slashes from the request path before filtering is applied, effectively mitigating the `input.parsed_path` issue described in this advisory.\n\n\n#### 2. Use `input.attributes.request.http.path` instead of `input.parsed_path` in policies\n\nThe `input.attributes.request.http.path` field contains the unprocessed, raw request path. Users are recommended to update any policy using `input.parsed_path` to instead use the `input.attributes.request.http.path` field.\n\n##### Example ####\n\n```rego\npackage example\n\n# Use instead of input.parsed_path\nparsed_path := split(                                        # tokenize into array\n\ttrim_left(                                               # drop leading slashes\n\t\turlquery.decode(input.attributes.request.http.path), # url-decode the path\n\t\t\"/\",\n\t),\n\t\"/\",\n)\n```",
  "id": "GHSA-9f29-v6mm-pw6w",
  "modified": "2026-02-19T21:56:34Z",
  "published": "2026-02-18T15:25:04Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/open-policy-agent/opa-envoy-plugin/security/advisories/GHSA-9f29-v6mm-pw6w"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-26205"
    },
    {
      "type": "WEB",
      "url": "https://github.com/open-policy-agent/opa-envoy-plugin/commit/58c44d4ec408d5852d1d0287599e7d5c5e2bc5c3"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/open-policy-agent/opa-envoy-plugin"
    },
    {
      "type": "WEB",
      "url": "https://github.com/open-policy-agent/opa-envoy-plugin/releases/tag/v1.13.2-envoy-2"
    }
  ],
  "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:N/SC:H/SI:H/SA:H",
      "type": "CVSS_V4"
    }
  ],
  "summary": "opa-envoy-plugin has an Authorization Bypass via Double-Slash Path Misinterpretation in input.parsed_path"
}

CVE-2026-26205 (GCVE-0-2026-26205)

Vulnerability from cvelistv5 – Published: 2026-02-19 19:31 – Updated: 2026-02-19 21:22

Title

opa-envoy-plugin has an Authorization Bypass via Double-Slash Path Misinterpretation in `input.parsed_path`

Summary

opa-envoy-plugun is a plugin to enforce OPA policies with Envoy. Versions prior to 1.13.2-envoy-2 have a vulnerability in how the `input.parsed_path` field is constructed. HTTP request paths are treated as full URIs when parsed; interpreting leading path segments prefixed with double slashes (`//`) as authority components, and therefore dropping them from the parsed path. This creates a path interpretation mismatch between authorization policies and backend servers, enabling attackers to bypass access controls by crafting requests where the authorization filter evaluates a different path than the one ultimately served. Version 1.13.2-envoy-2 fixes the issue.

Severity

7.1 (High)


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

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-02-19 20:54 UTC

CWE

CWE-863 - Incorrect Authorization

Assigner

GitHub_M mitre root

References

3 references

URL	Tags
https://github.com/open-policy-agent/opa-envoy-pl…	x_refsource_CONFIRM
https://github.com/open-policy-agent/opa-envoy-pl…	x_refsource_MISC
https://github.com/open-policy-agent/opa-envoy-pl…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
open-policy-agent	opa-envoy-plugin	Affected: < 1.13.2-envoy-2

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-26205",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-02-19T20:54:43.231111Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-02-19T21:22:21.384Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "opa-envoy-plugin",
          "vendor": "open-policy-agent",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 1.13.2-envoy-2"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "opa-envoy-plugun is a plugin to enforce OPA policies with Envoy. Versions prior to 1.13.2-envoy-2 have a vulnerability in how the `input.parsed_path` field is constructed. HTTP request paths are treated as full URIs when parsed; interpreting leading path segments prefixed with double slashes (`//`) as authority components, and therefore dropping them from the parsed path. This creates a path interpretation mismatch between authorization policies and backend servers, enabling attackers to bypass access controls by crafting requests where the authorization filter evaluates a different path than the one ultimately served. Version 1.13.2-envoy-2 fixes the issue."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "attackComplexity": "LOW",
            "attackRequirements": "PRESENT",
            "attackVector": "NETWORK",
            "baseScore": 7.1,
            "baseSeverity": "HIGH",
            "privilegesRequired": "NONE",
            "subAvailabilityImpact": "HIGH",
            "subConfidentialityImpact": "HIGH",
            "subIntegrityImpact": "HIGH",
            "userInteraction": "NONE",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:H",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "NONE"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-863",
              "description": "CWE-863: Incorrect Authorization",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-02-19T19:31:26.905Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/open-policy-agent/opa-envoy-plugin/security/advisories/GHSA-9f29-v6mm-pw6w",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/open-policy-agent/opa-envoy-plugin/security/advisories/GHSA-9f29-v6mm-pw6w"
        },
        {
          "name": "https://github.com/open-policy-agent/opa-envoy-plugin/commit/58c44d4ec408d5852d1d0287599e7d5c5e2bc5c3",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/open-policy-agent/opa-envoy-plugin/commit/58c44d4ec408d5852d1d0287599e7d5c5e2bc5c3"
        },
        {
          "name": "https://github.com/open-policy-agent/opa-envoy-plugin/releases/tag/v1.13.2-envoy-2",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/open-policy-agent/opa-envoy-plugin/releases/tag/v1.13.2-envoy-2"
        }
      ],
      "source": {
        "advisory": "GHSA-9f29-v6mm-pw6w",
        "discovery": "UNKNOWN"
      },
      "title": "opa-envoy-plugin has an Authorization Bypass via Double-Slash Path Misinterpretation in `input.parsed_path`"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-26205",
    "datePublished": "2026-02-19T19:31:26.905Z",
    "dateReserved": "2026-02-11T19:56:24.814Z",
    "dateUpdated": "2026-02-19T21:22:21.384Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

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.

Detection rules are retrieved from Rulezet.

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

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