SB2026110949 - Improper Certificate Validation in Cilium

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Main Vulnerability Database SB2026110949

SB2026110949 - Improper Certificate Validation in Cilium

Published: November 9, 2026

Security Bulletin ID SB2026110949
CSH Severity
Low
Patch available
YES
Number of vulnerabilities 1
Exploitation vector Adjecent network
Highest impact Data manipulation

Breakdown by Severity

Low 100%
  • Low
  • Medium
  • High
  • Critical

Description

This security bulletin contains information about 1 vulnerability.


1) Improper Certificate Validation (CVE-ID: CVE-2026-83620)

CWE-ID: CWE-295 - Improper Certificate Validation

CVSSv4: 7 [CVSS:4.0/AV:A/AC:L/AT:N/PR:L/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N]


The vulnerability allows a low-privileged adjacent-network attacker to bypass mutual authentication and impersonate any identity in a Cilium cluster with mutual authentication enabled.

The vulnerability exists due to improper certificate validation in Cilium mutual authentication when processing certificate chains during TLS handshakes. A low-privileged adjacent-network attacker with any valid client certificate can append a target identity's public certificate to their certificate chain and authenticate as that identity.


Remediation

Install update from vendor's website.

References