CVE-2026-26308
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.
AI Insight
LLM-synthesized narrative grounded in this CVE's description and references.
Affected packages
Versions sourced from the GitHub Security Advisory.
| Package | Affected versions | Patched versions |
|---|---|---|
github.com/envoyproxy/envoyGo | >= 1.37.0, < 1.37.1 | 1.37.1 |
github.com/envoyproxy/envoyGo | >= 1.36.0, < 1.36.5 | 1.36.5 |
github.com/envoyproxy/envoyGo | >= 1.35.0, < 1.35.9 | 1.35.9 |
github.com/envoyproxy/envoyGo | < 1.34.13 | 1.34.13 |
Affected products
5cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*+ 2 more
- cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*range: <1.34.13
- cpe:2.3:a:envoyproxy:envoy:1.37.0:*:*:*:*:*:*:*
- (no CPE)range: >= 1.37.0, < 1.37.1
- osv-coords2 versions
< 1.34.13+ 1 more
- (no CPE)range: < 1.34.13
- (no CPE)range: >= 1.37.0, < 1.37.1
Patches
Vulnerability mechanics
References
4- github.com/envoyproxy/envoy/commit/b6ba0b2294b98484fb0ed8556897d1073cc27867nvdPatchWEB
- github.com/envoyproxy/envoy/security/advisories/GHSA-ghc4-35x6-crw5nvdExploitMitigationVendor AdvisoryWEB
- github.com/advisories/GHSA-ghc4-35x6-crw5ghsaADVISORY
- nvd.nist.gov/vuln/detail/CVE-2026-26308ghsaADVISORY
News mentions
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