CVE-2026-26308
Fixed upstream EPSS <1%CVSS 7.5
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.
Products: envoyproxy envoy
Fixed upstream
| Ecosystem | Package | Fixed in |
|---|---|---|
| Go | github.com/envoyproxy/envoy | 1.37.1 |
| Go | github.com/envoyproxy/envoy | 1.36.5 |
| Go | github.com/envoyproxy/envoy | 1.35.9 |
| Go | github.com/envoyproxy/envoy | 1.34.13 |