sigstore legacy TUF client allows for arbitrary file writes with target cache path traversal

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

5.8 · CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:N/I:H/A:N

EPSS

• CVE-2026-24137: 0.39% estimated exploitation activity in the next 30 days; percentile 33.24 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary The legacy TUF client pkg/tuf/client.go, which supports caching target files to disk, constructs a filesystem path by joining a cache base directory with a target name sourced from signed target metadata, but it does not validate that the resulting path stays within the cache base directory. Note that this should only affect clients that are directly using the TUF client in sigstore/sigstore or are using an older version of Cosign. As this TUF client implementation is deprecated, users should migrate to https://github.com/sigstore/sigstore-go/tree/main/pkg/tuf as soon as possible. Note that this does not affect users of the public Sigstore deployment, where TUF metadata is validated by a quorum of trusted collaborators. Impact A malicious TUF repository can trigger arbitrary file overwriting, limited to the permissions that the calling process has. Workarounds Users can disable disk caching for the legacy client by setting SIGSTORENOCACHE=true in the environment, migrate to…

Published by the source

22 Jan 2026, 20:28 UTC

Last modified by the source

27 Feb 2026, 21:37 UTC

Source last checked

26 Oct 2026, 15:14 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-fcv2-xgw5-pqxf

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# Patch Next advisory brief: CVE-2026-24137

Advisory: sigstore legacy TUF client allows for arbitrary file writes with target cache path traversal
IDs: CVE-2026-24137, GHSA-fcv2-xgw5-pqxf
Record: https://patchnext.com/advisories/cve-2026-24137 (revision 1, source checked 26 Oct 2026, 15:14 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/sigstore/sigstore 1.10.4. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/sigstore/sigstore: affected <= 1.10.3; fixed in 1.10.4

## Suggested inspection (read-only)
- Go github.com/sigstore/sigstore: 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/sigstore/sigstore.
- 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-fcv2-xgw5-pqxf (GitHub-reviewed advisory GHSA-fcv2-xgw5-pqxf lists affected ranges: Go github.com/sigstore/sigstore >=0 <=1.10.3)

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