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PatchSiren cyber security CVE debrief

CVE-2026-40923 tektoncd CVE debrief

CVE-2026-40923 is a path traversal validation bypass in Tekton Pipelines. In affected versions before 1.11.1, the VolumeMount path restriction checks use a simple prefix test, which can be bypassed with .. components. As a result, a path such as /tekton/home/../results can satisfy validation while resolving at runtime to /tekton/results. The issue is fixed in Tekton Pipelines 1.11.1.

Vendor
tektoncd
Product
pipeline
CVSS
MEDIUM 5.4
CISA KEV
Not listed in stored evidence
Original CVE published
2026-04-21
Original CVE updated
2026-04-27
Advisory published
2026-04-21
Advisory updated
2026-04-27

Who should care

Operators and maintainers running Tekton Pipelines versions earlier than 1.11.1, especially in environments that rely on path restrictions for VolumeMounts under /tekton internal paths.

Technical summary

The weakness is a validation flaw: the restriction logic checks whether a path starts with the expected /tekton prefix using strings.HasPrefix, but does not normalize the path first with filepath.Clean. Because of that, traversal sequences like .. can let an attacker present a path that appears allowed during validation while resolving to a restricted internal location at runtime. NVD maps the issue to CWE-22 and gives it CVSS 3.1 vector AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N (5.4).

Defensive priority

Medium. The issue requires low privileges and has no availability impact, but it can affect confidentiality and integrity within the scope of the containerized pipeline environment.

Recommended defensive actions

  • Upgrade Tekton Pipelines to version 1.11.1 or later.
  • Review pipeline definitions and volume mount paths for any use of .. traversal components.
  • Validate that any path-based allowlist or restriction logic in your Tekton-related automation normalizes paths before comparing them.
  • After upgrading, re-test workload definitions that depend on /tekton path restrictions to confirm the fix behaves as expected.

Evidence notes

The CVE description states that the flaw exists prior to 1.11.1 and is caused by a path restriction check that uses strings.HasPrefix without filepath.Clean, allowing /tekton/home/../results to pass validation and resolve to /tekton/results. NVD marks the record as analyzed and lists CWE-22 with CVSS 3.1 AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N. The supplied official references point to the Tekton 1.11.1 release notes and the GitHub security advisory.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-40923 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-40923

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-40923 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-40923

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.