---
id: CVE-2026-73552
title: >-
  Envoy is an open source edge and service proxy designed for cloud-native
  applications
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 s…
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N'
cwe:
  - CWE-20
vendor: envoyproxy
product: envoy
affected:
  - envoy < 1.36.10
  - 'envoy >= 1.37.0, < 1.37.6'
  - 'envoy >= 1.38.0, < 1.38.4'
  - 'envoy >= 1.39.0, < 1.39.1'
published: '2026-09-21'
updated: '2026-09-23'
sourceUpdated: '2026-09-23T18:21:42.327'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-73552'
references:
  - url: >-
      https://github.com/envoyproxy/envoy/commit/5650cb9770d4420ec2bcbed8b90be06f564ecc07
    label: security-advisories@github.com
  - url: >-
      https://github.com/envoyproxy/envoy/commit/7d1dee5dda66434d84437cc5c85153aa03955e26
    label: security-advisories@github.com
  - url: >-
      https://github.com/envoyproxy/envoy/commit/c2b9a19dc081f03be6a9b4ca932673e5e7a33d18
    label: security-advisories@github.com
  - url: >-
      https://github.com/envoyproxy/envoy/commit/f3726765f3a12ddc76dcb52c0b79bec3d95ced1c
    label: security-advisories@github.com
  - url: 'https://github.com/envoyproxy/envoy/releases/tag/v1.36.10'
    label: security-advisories@github.com
  - url: 'https://github.com/envoyproxy/envoy/releases/tag/v1.37.6'
    label: security-advisories@github.com
  - url: 'https://github.com/envoyproxy/envoy/releases/tag/v1.38.4'
    label: security-advisories@github.com
  - url: 'https://github.com/envoyproxy/envoy/releases/tag/v1.39.1'
    label: security-advisories@github.com
  - url: >-
      https://github.com/envoyproxy/envoy/security/advisories/GHSA-23xh-2qxr-3xv8
    label: security-advisories@github.com
tags:
  - nvd
  - cve.org
epss: 0.00665
epssPercentile: 0.49618
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-09-22T14:15:40.919777Z'
ingestedAt: '2026-09-21T19:51:58.873Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.