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.
Published: 2026-09-21
Score: 7.5 High
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

No vendor fix or workaround currently provided.

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Tracking

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Advisories

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History

Mon, 21 Sep 2026 19:45:00 +0000

Type Values Removed Values Added
Description No description is available for this CVE. 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.
Title envoy: envoy: RBAC safe_regex fails to match non-UTF-8 HTTP header values Envoy: HTTP RBAC safe_regex can fail open on RFC-valid obs-text header values
Weaknesses CWE-20
References

Wed, 02 Sep 2026 22:15:00 +0000

Type Values Removed Values Added
First Time appeared Envoyproxy
Envoyproxy envoy
Vendors & Products Envoyproxy
Envoyproxy envoy

Tue, 01 Sep 2026 12:15:00 +0000

Type Values Removed Values Added
Description No description is available for this CVE.
Title envoy: envoy: RBAC safe_regex fails to match non-UTF-8 HTTP header values
Weaknesses CWE-863
References
Metrics threat_severity

None

cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N'}

threat_severity

Important


Subscriptions

Envoyproxy Envoy
cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-09-22T15:39:58.488Z

Reserved: 2026-08-12T20:53:46.380Z

Link: CVE-2026-73552

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-09-21T20:17:28.900

Modified: 2026-09-22T16:17:53.803

Link: CVE-2026-73552

cve-icon Redhat

Severity : Important

Publid Date: 2026-08-26T13:00:00Z

Links: CVE-2026-73552 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-09-21T21:00:07Z

Weaknesses
  • CWE-20

    Improper Input Validation

  • CWE-863

    Incorrect Authorization