CVE-2026-24137

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.

Workarounds

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.

A malicious TUF repository can trigger arbitrary file overwriting, limited to the permissions that the calling process has.

Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files. Typical impact: unauthorized file read or write outside the intended directory.

CVE-2026-24137 has a CVSS score of 5.8 (Medium). The vector is network-reachable, high privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.10.4); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2026-24137? CVE-2026-24137 is a medium-severity path traversal vulnerability in github.com/sigstore/sigstore (go), affecting versions <= 1.10.3. It is fixed in 1.10.4. Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files.
2. How severe is CVE-2026-24137? CVE-2026-24137 has a CVSS score of 5.8 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of github.com/sigstore/sigstore are affected by CVE-2026-24137? github.com/sigstore/sigstore (go) versions <= 1.10.3 is affected.
4. Is there a fix for CVE-2026-24137? Yes. CVE-2026-24137 is fixed in 1.10.4. Upgrade to this version or later.
5. Is CVE-2026-24137 exploitable, and should I be worried? Whether CVE-2026-24137 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-24137 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-24137? Upgrade github.com/sigstore/sigstore to 1.10.4 or later.