CVE-2026-25542: Tekton Pipelines: VerificationPolicy regex pattern bypass via substring matching

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-04-21 · updated 2026-10-26
Weakness: CWE-185

Description

Tekton Pipelines project provides k8s-style resources for declaring CI/CD-style pipelines. Starting in version 0.43.0 and prior to versions 1.0.2, 1.3.4, 1.6.2, 1.9.3, and 1.11.1, trusted resources verification policies match a resource source string (refSource.URI) against spec.resources[].pattern using regexp.MatchString. In Go, regexp.MatchString reports a match if the pattern matches anywhere in the string, so common unanchored patterns (including examples in tekton documentation) can be bypassed by attacker-controlled source strings that contain the trusted pattern as a substring. This can cause an unintended policy match and change which verification mode/keys apply. Versions 1.0.2, 1.3.4, 1.6.2, 1.9.3, and 1.11.1 fix the issue.

Affected products

tektoncd pipeline: from 0.43.0 before 1.11.0 — fixed in 1.11.0

How to fix

Upgrade to a fixed version: tektoncd pipeline 1.11.0. Check the vendor advisory for mitigations.

References

Get alerted when CVE-2026-25542 or the next vulnerability affects your stack