CVE-2026-26308
Envoy vulnerability analysis and mitigation

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.


SourceNVD

Related Envoy vulnerabilities:

CVE ID

Severity

Score

Technologies

Component name

CISA KEV exploit

Has fix

Published date

CVE-2026-26308HIGH8.2
  • EnvoyEnvoy
  • github.com/envoyproxy/envoy
NoYesMar 10, 2026
CVE-2026-26330HIGH7.5
  • EnvoyEnvoy
  • envoy
NoYesMar 10, 2026
CVE-2026-26310HIGH7.5
  • EnvoyEnvoy
  • cpe:2.3:a:envoyproxy:envoy
NoYesMar 10, 2026
CVE-2026-26311MEDIUM5.9
  • EnvoyEnvoy
  • cpe:2.3:a:envoyproxy:envoy
NoYesMar 10, 2026
CVE-2026-26309MEDIUM5.3
  • EnvoyEnvoy
  • cpe:2.3:a:envoyproxy:envoy
NoYesMar 10, 2026

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