Vulnerability Report

CVE-2026-26308

Title: RBAC Bypass via Duplicate HTTP Headers in Envoy

Other

Proof Of Concept

No public PoC currently indexed for CVE-2026-26308.

CWE Category CWE-863
Published Date Mar 10, 2026
Modified Date Mar 11, 2026
Exploit Status Not Found
Score 7.5 CVSS v3.1
Exploit Probability (EPSS)
0.29%

Vulnerability Summary

CVE-2026-26308: 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.

Impacted Vendors

E
enphase 1
E
envoyproxy 1

Reference Links

https://github.com/envoyproxy/envoy/commit/b6ba0b2294b98484fb0ed8556897d1073cc27867 https://github.com/envoyproxy/envoy/security/advisories/GHSA-ghc4-35x6-crw5
CVSS v3.1
Source Entity [email protected]
Severity HIGH
7.5
Attack Vector
NETWORK
Complexity
HIGH
Privileges
N/A
Interaction
NONE
Confidentiality
N/A
Integrity
N/A
Availability
N/A
Scope
CHANGED
RAW VECTOR CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:L/A:N
CVSS v3.1
Source Entity [email protected]
Severity HIGH
8.2
Attack Vector
NETWORK
Complexity
LOW
Privileges
N/A
Interaction
NONE
Confidentiality
N/A
Integrity
N/A
Availability
N/A
Scope
UNCHANGED
RAW VECTOR CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N

Associated Attack Patterns (CAPEC)

Total: Patterns

CVE-2026-26308 Exploits & PoCs (Proof Of Concept)

No public PoCs found in our database for this CVE.

MODIFIED

Vulnerability data updated via NVD.

MODIFIED

Vulnerability data updated via NVD.

MODIFIED

Vulnerability data updated via NVD.

MODIFIED

Vulnerability data updated via NVD.

Attack Vector Matrix

Access Vector NETWORK
Complexity HIGH
Privileges N/A
Interaction NONE
CVSS Vector String CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:L/A:N

Affected Stack

No specific products linked.