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Medium, CVSS 5.4

Tekton Pipelines: VolumeMount path restriction bypass via missing filepath.Clean in /tekton/ check

CVE-2026-40923GHSA-rx35-6rhx-7858

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (github.com/tektoncd/pipeline 1.11.1, 1.9.3, 1.6.2, 1.3.4, 1.0.2), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

  • Go github.com/tektoncd/pipeline

    Affected
    >= 1.10.0, < 1.11.1>= 1.7.0, < 1.9.3>= 1.4.0, < 1.6.2>= 1.2.0, < 1.3.4>= 1.0.0, < 1.0.2
    Fixed in
    1.0.2, 1.11.1, 1.9.3, 1.6.2, 1.3.4

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
5.4 · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
EPSS
  • CVE-2026-40923: 0.22% estimated exploitation activity in the next 30 days; percentile 12.65 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Summary A validation bypass in the VolumeMount path restriction allows mounting volumes under restricted /tekton/ internal paths by using .. path traversal components. The restriction check uses strings.HasPrefix without filepath.Clean, so a path like /tekton/home/../results passes validation but resolves to /tekton/results at runtime. Details Tekton Pipelines restricts VolumeMount paths under /tekton/ (except /tekton/home) to prevent users from interfering with internal execution state. The validation at pkg/apis/pipeline/v1/containervalidation.go checks mount paths using strings.HasPrefix without normalizing the path first: Because /tekton/home is an allowed prefix, a path like /tekton/home/../results passes both checks. At runtime, the container runtime resolves .. and the actual mount point becomes /tekton/results. The same pattern exists in pkg/apis/pipeline/v1beta1/taskvalidation.go. Impact An authenticated user with Task or TaskRun creation permissions can mount volumes over…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 1 · created ·

    Published from ghsa record GHSA-rx35-6rhx-7858

Agent brief

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# Patch Next advisory brief: CVE-2026-40923

Advisory: Tekton Pipelines: VolumeMount path restriction bypass via missing filepath.Clean in /tekton/ check
IDs: CVE-2026-40923, GHSA-rx35-6rhx-7858
Record: https://patchnext.com/advisories/cve-2026-40923 (revision 1, source checked 26 Oct 2026, 15:22 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.4)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/tektoncd/pipeline 1.11.1, 1.9.3, 1.6.2, 1.3.4, 1.0.2. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/tektoncd/pipeline: affected >= 1.10.0, < 1.11.1; >= 1.7.0, < 1.9.3; >= 1.4.0, < 1.6.2; >= 1.2.0, < 1.3.4; >= 1.0.0, < 1.0.2; fixed in 1.0.2, 1.11.1, 1.9.3, 1.6.2, 1.3.4

## Suggested inspection (read-only)
- Go github.com/tektoncd/pipeline: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/tektoncd/pipeline.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-rx35-6rhx-7858 (GitHub-reviewed advisory GHSA-rx35-6rhx-7858 lists affected ranges: Go github.com/tektoncd/pipeline >=1.10.0 =1.7.0 =1.4.0 =1.2.0 =1.0.0 <1.0.2)

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