CVE-2026-73552 (GCVE-0-2026-73552)

Vulnerability from cvelistv5 – Published: 2026-09-21 19:37 – Updated: 2026-09-21 19:37
VLAI
Title
Envoy: HTTP RBAC safe_regex can fail open on RFC-valid obs-text header values
Summary
Envoy is an open source edge and service proxy designed for cloud-native applications. Prior to 1.36.10, 1.37.6, 1.38.4, and 1.39.1, Envoy HTTP RBAC accepts RFC-valid opaque header bytes but evaluates safe_regex values with RE2's UTF-8 subject semantics. A downstream client can preserve a prohibited marker and add an unrelated obs-text octet, causing RE2::FullMatch to return false and a negative RBAC policy to treat the invalid subject as an ordinary no-match. A byte-oriented route matcher can still observe the marker, allowing the request to reach a route intended to be denied. The relevant scope boundary is that plain positive ALLOW regexes normally fail closed, and exact, prefix, suffix, and contains matchers are not shown to have this subject-domain failure. This issue is fixed in versions 1.36.10, 1.37.6, 1.38.4, and 1.39.1.
Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
CWE
  • CWE-20 - Improper Input Validation
Assigner
References
Impacted products
Vendor Product Version CPE status
envoyproxy envoy Affected: < 1.36.10
Affected: >= 1.37.0, < 1.37.6
Affected: >= 1.38.0, < 1.38.4
Affected: >= 1.39.0, < 1.39.1
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{
  "containers": {
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      "affected": [
        {
          "product": "envoy",
          "vendor": "envoyproxy",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 1.36.10"
            },
            {
              "status": "affected",
              "version": "\u003e= 1.37.0, \u003c 1.37.6"
            },
            {
              "status": "affected",
              "version": "\u003e= 1.38.0, \u003c 1.38.4"
            },
            {
              "status": "affected",
              "version": "\u003e= 1.39.0, \u003c 1.39.1"
            }
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      "descriptions": [
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          "lang": "en",
          "value": "Envoy is an open source edge and service proxy designed for cloud-native applications. Prior to 1.36.10, 1.37.6, 1.38.4, and 1.39.1, Envoy HTTP RBAC accepts RFC-valid opaque header bytes but evaluates safe_regex values with RE2\u0027s UTF-8 subject semantics. A downstream client can preserve a prohibited marker and add an unrelated obs-text octet, causing RE2::FullMatch to return false and a negative RBAC policy to treat the invalid subject as an ordinary no-match. A byte-oriented route matcher can still observe the marker, allowing the request to reach a route intended to be denied. The relevant scope boundary is that plain positive ALLOW regexes normally fail closed, and exact, prefix, suffix, and contains matchers are not shown to have this subject-domain failure. This issue is fixed in versions 1.36.10, 1.37.6, 1.38.4, and 1.39.1."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 7.5,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
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              "description": "CWE-20: Improper Input Validation",
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        "shortName": "GitHub_M"
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          "name": "https://github.com/envoyproxy/envoy/security/advisories/GHSA-23xh-2qxr-3xv8",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/envoyproxy/envoy/security/advisories/GHSA-23xh-2qxr-3xv8"
        },
        {
          "name": "https://github.com/envoyproxy/envoy/commit/5650cb9770d4420ec2bcbed8b90be06f564ecc07",
          "tags": [
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          "url": "https://github.com/envoyproxy/envoy/commit/5650cb9770d4420ec2bcbed8b90be06f564ecc07"
        },
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          "tags": [
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          "url": "https://github.com/envoyproxy/envoy/commit/7d1dee5dda66434d84437cc5c85153aa03955e26"
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          "tags": [
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          "url": "https://github.com/envoyproxy/envoy/commit/c2b9a19dc081f03be6a9b4ca932673e5e7a33d18"
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          "tags": [
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          ],
          "url": "https://github.com/envoyproxy/envoy/commit/f3726765f3a12ddc76dcb52c0b79bec3d95ced1c"
        },
        {
          "name": "https://github.com/envoyproxy/envoy/releases/tag/v1.36.10",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/envoyproxy/envoy/releases/tag/v1.36.10"
        },
        {
          "name": "https://github.com/envoyproxy/envoy/releases/tag/v1.37.6",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/envoyproxy/envoy/releases/tag/v1.37.6"
        },
        {
          "name": "https://github.com/envoyproxy/envoy/releases/tag/v1.38.4",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/envoyproxy/envoy/releases/tag/v1.38.4"
        },
        {
          "name": "https://github.com/envoyproxy/envoy/releases/tag/v1.39.1",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/envoyproxy/envoy/releases/tag/v1.39.1"
        }
      ],
      "source": {
        "advisory": "GHSA-23xh-2qxr-3xv8",
        "discovery": "UNKNOWN"
      },
      "title": "Envoy: HTTP RBAC safe_regex can fail open on RFC-valid obs-text header values"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-73552",
    "datePublished": "2026-09-21T19:37:20.546Z",
    "dateReserved": "2026-08-12T20:53:46.380Z",
    "dateUpdated": "2026-09-21T19:37:20.546Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "nvd": {
      "cve": {
        "affected": [
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                "product": "envoy",
                "vendor": "envoyproxy",
                "versions": [
                  {
                    "status": "affected",
                    "version": "\u003c 1.36.10"
                  },
                  {
                    "status": "affected",
                    "version": "\u003e= 1.37.0, \u003c 1.37.6"
                  },
                  {
                    "status": "affected",
                    "version": "\u003e= 1.38.0, \u003c 1.38.4"
                  },
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                    "version": "\u003e= 1.39.0, \u003c 1.39.1"
                  }
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            "source": "security-advisories@github.com"
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        "cveTags": [],
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          }
        ],
        "id": "CVE-2026-73552",
        "lastModified": "2026-09-21T20:17:28.900",
        "metrics": {
          "cvssMetricV31": [
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                "attackComplexity": "LOW",
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        "vulnStatus": "Received",
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            "type": "Primary"
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  }
}



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