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🛡️ CVE-2026-40923 — tekton-pipelines

🟡 CVSS 5.4 — Medium ✅ No Known Exploit CWE-22 NVD
5.4
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

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

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/container_validation.go checks mount paths using

strings.HasPrefix without normalizing the path first:

```go

if strings.HasPrefix(vm.MountPath, "/tekton/") &&

!strings.HasPrefix(vm.MountPath, "/tekton/home") {

// reject

}

```

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/task_validation.go.

Impact

An authenticated user with Task or TaskRun creation permissions can

mount volumes over internal Tekton paths, potentially:

  • Writing fake task results that downstream pipelines trust
  • Reading or modifying step scripts before execution
  • Interfering with entrypoint coordination state

Patches

_(to be filled: fixed in versions X.Y.Z)_

Workarounds

  • Use admission controllers (OPA/Gatekeeper, Kyverno) to validate that

VolumeMount paths do not contain .. components.

  • In multi-tenant setups, restrict who can create Task and TaskRun

resources via RBAC.

Affected Versions

All versions through v1.10.0 (both v1 and v1beta1 APIs).

Acknowledgments

This vulnerability was reported by @kodareef5.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs low-level privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality low, integrity low, availability none.

CVSS metrics in full

The score comes from this vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N

  • Attack vector: Network — reachable from anywhere that can route to the service.
  • Attack complexity: Low — the attack works reliably, with no preparation.
  • Privileges required: Low — an ordinary user account is enough.
  • User interaction: None — nobody has to be tricked into anything.
  • Scope: Unchanged — the damage stays inside the vulnerable component.
  • Confidentiality impact: Low — limited, and the attacker does not choose what is affected.
  • Integrity impact: Low — limited, and the attacker does not choose what is affected.
  • Availability impact: None.

Weakness class

CVE-2026-40923 is classified as CWE-22: Path Traversal. A file path built from user input is not confined to the intended directory, letting an attacker reach files elsewhere on the filesystem.

Affected software

CVE-2026-40923 is recorded against 2 packages.

  • github.com/tektoncd/pipeline
  • tekton-pipelines (fixed in 1.11.1)

Timeline and source

Published on 21 April 2026 and last revised on 23 July 2026. No public exploit is currently recorded for this entry. Record sourced from NVD.

References

github.com (Web)
nvd.nist.gov (Advisory)
github.com (Package)
github.com (Web)

Other advisories for this package

github.com/tektoncd/pipeline has other advisories on record. If you are patching this one, these are worth checking on the same host:

Same weakness in other software

These advisories are the same class of weakness (CWE-22: Path Traversal) in other software:

Details

Severity Medium
CVSS Score 5.4
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
CWE CWE-22
Public Exploit ✅ No
Source NVD
Published 2026-04-21
Updated 2026-08-20
Modified 2026-07-23
Fix URL N/A

Affected Packages

Software From version Fixed in
github.com/tektoncd/pipeline — —
tekton-pipelines — 1.11.1

Similar Threats

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