Envoy has an RBAC Header Validation Bypass via Multi-Value Header Concatenation
- Published
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- Fix
- Fixed in 1.37.1, 1.36.5, 1.35.9, 1.34.13
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
- Exploitation: none
- Automatable: no
- Technical impact: partial
Summary
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.
Timeline
- CVE published
- CISA SSVC assessment
Exploitation: none · Automatable: no · Technical impact: partial
- Record last updated
Affected versions
- envoyproxy envoy
From 1.37.0 · fixed in 1.37.1; From 1.36.0 · fixed in 1.36.5; From 1.35.0 · fixed in 1.35.9; fixed in 1.34.13
- github.com/envoyproxy/envoyGo
From 1.37.0 · fixed in 1.37.1
- github.com/envoyproxy/envoyGo
From 1.36.0 · fixed in 1.36.5
- github.com/envoyproxy/envoyGo
From 1.35.0 · fixed in 1.35.9
- github.com/envoyproxy/envoyGo
fixed in 1.34.13