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Vulnerabilities

Vulnerability · CVE-2026-26308

Envoy is a high-performance edge/middle/service proxy.

Published Mar 10, 2026 · catalog updated Jun 17, 2026 · Envoy is a high-performance

Check if you run it

No confirmed exploitation is on record for CVE-2026-26308. EPSS is 0.36%. Act only if a listed version of Envoy is a high-performance is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (Envoy is a high-performance).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High8.2
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.36%
Remediation
Advisory link
Affected products
cpe envoyproxy/envoy

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe envoyproxy/envoy1.37.0

How to fix CVE-2026-26308

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-26308. EPSS is 0.36%. Act only if a listed version of Envoy is a high-performance is installed.

Which versions are affected?

Compare what you have installed with 1.37.0. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-863: Incorrect Authorization. EPSS 0.36%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Mar 10, 2026 · NIST NVD

    Detected

    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

  2. Jun 17, 2026 · NIST NVD

    Updated

    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

Sources

  • CVE.orgVulnerability recordCVE-2026-26308

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-26308

    30-day exploitation probability 0.4%

    first.org
  • NIST NVDVulnerability recordCVE-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. Instea

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.