CVE-2026-73552: Envoy: HTTP RBAC safe_regex can fail open on RFC-valid obs-text header values
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.
Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N · CWE-20
Tracked companies
Mapped from the CVE’s affected-product data, NVD CPE matches, vendor advisories or package feeds. A mapping means the vendor’s software is named, not that its hosted service was exposed.
Status incidents that name it
No tracked status incident names this CVE.
Affected vendors and products
envoyproxy: envoy
References
- CVE record on cve.org (opens in new tab)
- NVD entry (opens in new tab)
- github.com/envoyproxy/envoy/commit/5650cb9770d4420ec2bcbed8b90be06f564ecc07 (opens in new tab)
- github.com/envoyproxy/envoy/commit/7d1dee5dda66434d84437cc5c85153aa03955e26 (opens in new tab)
- github.com/envoyproxy/envoy/commit/c2b9a19dc081f03be6a9b4ca932673e5e7a33d18 (opens in new tab)
- github.com/envoyproxy/envoy/commit/f3726765f3a12ddc76dcb52c0b79bec3d95ced1c (opens in new tab)
- github.com/envoyproxy/envoy/releases/tag/v1.36.10 (opens in new tab)
- github.com/envoyproxy/envoy/releases/tag/v1.37.6 (opens in new tab)
- github.com/envoyproxy/envoy/releases/tag/v1.38.4 (opens in new tab)
- github.com/envoyproxy/envoy/releases/tag/v1.39.1 (opens in new tab)
- github.com/envoyproxy/envoy/security/advisories/GHSA-23xh-2qxr-3xv8 (opens in new tab)
- CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (opens in new tab)
- This product uses data from the NVD API but is not endorsed or certified by the NVD. (opens in new tab)
- Known Exploited Vulnerabilities catalog from CISA. (opens in new tab)
- EPSS scores from FIRST (Exploit Prediction Scoring System). (opens in new tab)