Is CVE-2026-26308 actively exploited?

CVE-2026-26308 has no public evidence of in-the-wild exploitation as of 2026-03-11.

What is the CVSS score for CVE-2026-26308?

CVE-2026-26308 has a CVSS score of 7.5 (HIGH severity). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:L/A:N.

How do I patch CVE-2026-26308?

Patch guidance is available from envoyproxy security advisories. CVEDatabase generates AI-assisted remediation guidance on demand for CVE-2026-26308.

Fix CVE-2026-26308 - HIGH envoyproxy envoy

Q: Which products are affected by CVE-2026-26308?

4 products: envoyproxy envoy, envoyproxy envoy, envoyproxy envoy, envoyproxy envoy.

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.

CVSS Metrics

Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:L/A:N
Attack Vector: network
Complexity: high
Privileges: none
User Action: none
Scope: changed
Confidentiality: high
Integrity: low
Availability: none
Weaknesses: CWE-863 · Incorrect Authorization

Metadata

Primary Vendor: ENVOYPROXY
Published: 3/10/2026
Last Modified: 3/11/2026
Source: NIST NVD
Note: Verify all details with official vendor sources before applying patches.

Affected Products

envoyproxy : envoyenvoyproxy : envoyenvoyproxy : envoyenvoyproxy : envoy

Remediation Guidance

Executive Summary

Cite this page

CVE-2026-26308. CVEDatabase.com. Retrieved 1 May 2026. https://cvedatabase.com/cve/CVE-2026-26308

View on NIST NVD

CVE-2026-26308 vulnerability