CVE-2026-24137 sigstore legacy TUF client allows for arbitrary file writes with target cache path traversal
A malicious TUF repository can overwrite arbitrary files via path traversal in the legacy TUF client's target caching mechanism.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-24137?
CVE-2026-24137 is a medium-severity path traversal vulnerability in sigstore, published on 23 Jan 2026. An attacker needs administrator access to exploit it, with no action from the victim.
Official description
sigstore framework is a common go library shared across sigstore services and clients. In versions 1.10.3 and below, the legacy TUF client (pkg/tuf/client.go) supports caching target files to disk. It constructs a filesystem path by joining a cache base directory with a target name sourced from signed target metadata; however, it does not validate that the resulting path stays within the cache base directory. A malicious TUF repository can trigger arbitrary file overwriting, limited to the permissions that the calling process has. 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. Public Sigstore deployment users are unaffected, as TUF metadata is validated by a quorum of trusted collaborators. This issue has been fixed in version 1.10.4. As a workaround, users can disable disk caching for the legacy client by setting SIGSTORE_NO_CACHE=true in the environment, migrate to https://github.com/sigstore/sigstore-go/tree/main/pkg/tuf, or upgrade to the latest sigstore/sigstore release.
Weakness: CWE-22
Which versions are affected by CVE-2026-24137?
3 open source packages ship an affected version, including github.com/sigstore/sigstore.
| Package | Affected | Fixed in |
|---|---|---|
github.com/sigstore/sigstore Go | All versions | 1.10.4 |
github.com/sigstore/sigstore Go | All versions | 1.10.4 |
github.com/sigstore/sigstore Go | All versions | 1.10.4 |
How do I fix CVE-2026-24137?
Upgrade github.com/sigstore/sigstore to 1.10.4 or later.
Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.
Is CVE-2026-24137 being exploited?
There is no known exploitation of CVE-2026-24137 in the wild and no public exploit code.
Sources
Also known as CLEANSTART-2026-LE66959, CLEANSTART-2026-UR24822, DEBIAN-CVE-2026-24137, GHSA-fcv2-xgw5-pqxf, GO-2026-4358, MINI-2xr2-m35j-74cf and 32 more.