CVE-2026-73552
Envoy: HTTP RBAC safe_regex can fail open on RFC-valid obs-text header values
- Published
- Updated
- Reserved
- Assigned by
- GitHub_M
Description
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.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_MCNA (assigner) | 3.1 | High7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N |
| NVDNVD · Analyzed | 3.1 | High7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N |
- EPSS (exploitation in 30 days)
- 0.49% · top 58% of all CVEs (6 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: yes · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.5.
Weakness
Affected products
- 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
References (9)
- https://github.com/envoyproxy/envoy/security/advisories/GHSA-23xh-2qxr-3xv8 (opens in a new tab)x_refsource_CONFIRM
- https://github.com/envoyproxy/envoy/commit/5650cb9770d4420ec2bcbed8b90be06f564ecc07 (opens in a new tab)x_refsource_MISC
- https://github.com/envoyproxy/envoy/commit/7d1dee5dda66434d84437cc5c85153aa03955e26 (opens in a new tab)x_refsource_MISC
- https://github.com/envoyproxy/envoy/commit/c2b9a19dc081f03be6a9b4ca932673e5e7a33d18 (opens in a new tab)x_refsource_MISC
- https://github.com/envoyproxy/envoy/commit/f3726765f3a12ddc76dcb52c0b79bec3d95ced1c (opens in a new tab)x_refsource_MISC
- https://github.com/envoyproxy/envoy/releases/tag/v1.36.10 (opens in a new tab)x_refsource_MISC
- https://github.com/envoyproxy/envoy/releases/tag/v1.37.6 (opens in a new tab)x_refsource_MISC
- https://github.com/envoyproxy/envoy/releases/tag/v1.38.4 (opens in a new tab)x_refsource_MISC
- https://github.com/envoyproxy/envoy/releases/tag/v1.39.1 (opens in a new tab)x_refsource_MISC
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2026-73552)Record last updated .