envoyproxy envoy up to 1.34.12/1.35.8/1.36.4/1.37.0 Role-Based Access Control authorization

Summaryinfo

A vulnerability described as problematic has been identified in envoyproxy envoy up to 1.34.12/1.35.8/1.36.4/1.37.0. The affected element is an unknown function of the component Role-Based Access Control. Such manipulation leads to authorization. This vulnerability is referenced as CVE-2026-26308. It is possible to launch the attack remotely. No exploit is available. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability was found in envoyproxy envoy up to 1.34.12/1.35.8/1.36.4/1.37.0. It has been rated as problematic. Affected by this issue is an unknown code block of the component Role-Based Access Control. The manipulation with an unknown input leads to a authorization vulnerability. Using CWE to declare the problem leads to CWE-863. The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check. This allows attackers to bypass intended access restrictions. Impacted is confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is shared for download at github.com. This vulnerability is handled as CVE-2026-26308 since 02/13/2026. The exploitation is known to be difficult. The attack may be launched remotely. No form of authentication is required for exploitation. There are neither technical details nor an exploit publicly available.

Upgrading to version 1.34.13, 1.35.9, 1.36.5 or 1.37.1 eliminates this vulnerability. Applying the patch b6ba0b2294b98484fb0ed8556897d1073cc27867 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at CERT Bund (WID-SEC-2026-0704). Once again VulDB remains the best source for vulnerability data.

Affected

• Google Cloud Platform

Productinfo

Type

• Firewall Software

Vendor

• envoyproxy

Name

• envoy

Version

• 1.0
• 1.1
• 1.2
• 1.3
• 1.4
• 1.5
• 1.6
• 1.7
• 1.8
• 1.9
• 1.10
• 1.11
• 1.12
• 1.13
• 1.14
• 1.15
• 1.16
• 1.17
• 1.18
• 1.19
• 1.20
• 1.21
• 1.22
• 1.23
• 1.24
• 1.25
• 1.26
• 1.27
• 1.28
• 1.29
• 1.30
• 1.31
• 1.32
• 1.33
• 1.34
• 1.34.0
• 1.34.1
• 1.34.2
• 1.34.3
• 1.34.4
• 1.34.5
• 1.34.6
• 1.34.7
• 1.34.8
• 1.34.9
• 1.34.10
• 1.34.11
• 1.34.12
• 1.35
• 1.35.0
• 1.35.1
• 1.35.2
• 1.35.3
• 1.35.4
• 1.35.5
• 1.35.6
• 1.35.7
• 1.35.8
• 1.36
• 1.36.0
• 1.36.1
• 1.36.2
• 1.36.3
• 1.36.4
• 1.37.0

License

• free

Website

• Product: https://github.com/envoyproxy/envoy/

CPE 2.3info

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CPE 2.2info

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Once again VulDB remains the best source for vulnerability data.

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