Reference page — cumulative record through Thursday, October 8, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.

CVE-2026-73552

CVE-2026-73552HIGH

envoyproxy envoy — Envoy: HTTP RBAC safe_regex can fail open on RFC-valid obs-text header values

  AV  AC  PR  UI  S  C  I  A   CVSS    EPSS   %ile   KEV
   N   L   N   N  U  H  N  N    7.5   .0047   38.9     —

AFFECTED
  Product  Versions     Fixed
  envoy    < 1.36.10 –  —

TIMELINE
  Aug 12  Reserved by GitHub_M
  Sep 21  Published (CNA: GitHub_M)
  Oct 5   EXPLOIT PUBLISHED — CVE-2026-73552 (envoyproxy envoy). Public exploit reference added.

CWE-20 · CNA: GitHub_M · CVSS v3.1 · 9 references · NVD status: Analyzed

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.

Lifecycle

Complete event history — 3 events, chronological
Date	Event	Detail
August 12, 2026	Reserved	Reserved by GitHub_M
September 21, 2026	Published	Published (CNA: GitHub_M)
October 5, 2026	EXPLOIT PUBLISHED	EXPLOIT PUBLISHED — CVE-2026-73552 (envoyproxy envoy). Public exploit reference added.

Affected

Affected products and packages — 1 row
Vendor	Product / Package	Ecosystem	Version introduced	Fixed
envoyproxy	envoy	—	< 1.36.10	—

Weaknesses

CWE-20

References (9)

https://github.com/envoyproxy/envoy/commit/5650cb9770d4420ec2bcbed8b90be06f564ecc07 [Patch]
https://github.com/envoyproxy/envoy/commit/7d1dee5dda66434d84437cc5c85153aa03955e26 [Patch]
https://github.com/envoyproxy/envoy/commit/c2b9a19dc081f03be6a9b4ca932673e5e7a33d18 [Patch]
https://github.com/envoyproxy/envoy/commit/f3726765f3a12ddc76dcb52c0b79bec3d95ced1c [Patch]
https://github.com/envoyproxy/envoy/releases/tag/v1.36.10 [Release Notes]
https://github.com/envoyproxy/envoy/releases/tag/v1.37.6 [Release Notes]
https://github.com/envoyproxy/envoy/releases/tag/v1.38.4 [Release Notes]
https://github.com/envoyproxy/envoy/releases/tag/v1.39.1 [Release Notes]
https://github.com/envoyproxy/envoy/security/advisories/GHSA-23xh-2qxr-3xv8 [Exploit, Vendor Advisory]

Authoritative record: CVE-2026-73552 at cve.org

Vendors: envoyproxy

Weaknesses: CWE-20

About this page

This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2026-73552 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Thursday, October 8, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.