GHSA-r7vq-6425-j94w
Python-TUF vulnerable to incorrect threshold signature computation for new root metadata
Blast Radius
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Description
Impact
The function _verify_root_self_signed(), introduced in v0.14.0, and which verifies self-signatures in a new root metadata file, counted multiple signatures by any new root key towards the new threshold. That is, any single new root key could theoretically provide enough signatures to meet the threshold for new key self-signatures required during root metadata update.
A scenario where this attack could be relevant is amazingly unlikely in practice to the point where labeling this issue as a security advisory is potentially overstating the impact of the issue. Given that new root keys only become trusted by the client after a successful root metadata update, which also requires the quorum of signatures from old trusted root keys, this issue has been evaluated as low in severity.
In particular, in order to exploit this vulnerability, an attacker must:
- Control one new root key.
- Craft a new root metadata file such that there is a number of signatures by this new root key greater than or equal to the new threshold.
- Cause a valid threshold of the old root keys to sign this new root metadata file.
- Cause this new root metadata file to be published on the repository.
- Cause clients to rotate to this new root metadata file.
Patches
A fix is available since version 0.16.0.
Workarounds
No workarounds are known for this issue.
References
- Pull request resolving the issue PR 1218
- Pull request which introduced the faulty computation of signature threshold on new root metadata PR 1101
- A similar previous issue with incorrectly computed signature thresholds in tuf is described in GHSA-pwqf-9h7j-7mv8
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | tuf | ≥ 0.14.0&&< 0.16.0 | 0.16.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for tuf. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update tuf to 0.16.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-r7vq-6425-j94w is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-r7vq-6425-j94w is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-r7vq-6425-j94w. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-r7vq-6425-j94w in your dependencies?
O3 detects GHSA-r7vq-6425-j94w across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.