CVE-2026-25542 is a medium-severity (CVSS 6.5) CWE-185 vulnerability in github.com/tektoncd/pipeline. O3 Security confirms whether CVE-2026-25542 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Tekton Pipelines: VerificationPolicy regex pattern bypass via substring matching
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2026-25542 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 356,453 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
github.com/tektoncd/pipeline🐹github.com/tektoncd/pipeline🐹github.com/tektoncd/pipeline🐹github.com/tektoncd/pipeline🐹github.com/tektoncd/pipelineReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
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 Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/tektoncd/pipeline | ≥ 0.43.0&&< 1.0.2 | 1.0.2 |
| 🐹Go | github.com/tektoncd/pipeline | ≥ 1.2.0&&< 1.3.4 | 1.3.4 |
| 🐹Go | github.com/tektoncd/pipeline | ≥ 1.4.0&&< 1.6.2 | 1.6.2 |
| 🐹Go | github.com/tektoncd/pipeline | ≥ 1.7.0&&< 1.9.3 | 1.9.3 |
| 🐹Go | github.com/tektoncd/pipeline | ≥ 1.10.0&&< 1.11.1 | 1.11.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/tektoncd/pipeline. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update github.com/tektoncd/pipeline to 1.0.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-25542 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-25542 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-25542. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-25542 in your dependencies?
O3 detects CVE-2026-25542 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.