CVEvulnerability

CVE-2026-26308

8.2 HIGH Published 2026-03-10 Modified 2026-06-17 Official page ↗
Status
Analyzed
Published
2026-03-10
Last modified
2026-06-17
Assigner
[email protected]
CVSS 3.1 ([email protected])
7.5 HIGH — CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:L/A:N
CVSS 3.1 ([email protected])
8.2 HIGH — CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N
Weaknesses
CWE-863

Description

Envoy is a high-performance edge/middle/service proxy. Prior to 1.37.1, 1.36.5, 1.35.8, and 1.34.13, the Envoy RBAC (Role-Based Access Control) filter contains a logic vulnerability in how it validates HTTP headers when multiple values are present for the same header name. Instead of validating each header value individually, Envoy concatenates all values into a single comma-separated string. This behavior allows attackers to bypass RBAC policies—specifically "Deny" rules—by sending duplicate headers, effectively obscuring the malicious value from exact-match mechanisms. This vulnerability is fixed in 1.37.1, 1.36.5, 1.35.8, and 1.34.13.

Affected configurations

• envoyproxy envoy (< 1.34.13) • envoyproxy envoy (>= 1.35.0 < 1.35.8) • envoyproxy envoy (>= 1.36.0 < 1.36.5) • envoyproxy envoy 1.37.0

Related

Weakness · CWE (1)

  • CWE-863 Incorrect Authorization weakness

References