GHSA-3633-5h82-39pq
Go-tuf Improperly handles multiple key IDs for the same public keys in attacker-controlled metadata
Blast Radius
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Description
Issue
If an attacker is able to control a threshold of keys to insert the same public key more than once with different key IDs into signed, trusted metadata on a TUF repository, then go-tuf clients < 0.3.2 are susceptible to an attack where attackers can cause the same signature from the same public key to be counted more than once against the threshold of signatures because they were mistakenly distinguished due to having different key IDs.
For example, suppose that in the root metadata file, there were a threshold of 2 self-signatures required from 2 different keys $K_A$ and $K_B$ belonging to Alice and Bob respectively. Bob has either mistakenly or maliciously produced a signed a malicious version of the root metadata file where Alice's key is listed once with the keyid $SHA2_{256}(K_A)$, but his public key is listed twice, once with the keyid $SHA2_{256}(K_B)$, and the other with $SHA2_{512}(K_B)$. If Bob can convince Alice to mistakenly sign this root metadata file without noticing this error, then clients < 0.3.2 would mistakenly count the same signature from Bob twice, once with the keyid $SHA2_{256}(K_B)$, and the other with $SHA2_{512}(K_B)$.
Impact
While the impact is potentially high, the severity is low as it requires either attackers or the repository (deliberately or mistakenly respectively) to have produced such an incorrect distribution of public keys, causing clients < 0.3.2 to fall prey to this issue.
Patches
A fix is available for clients with versions >= 0.3.2.
Workarounds
Users can work around this vulnerability in previous clients by checking for and removing duplicate public keys with different key IDs (e.g., SHA2-256 and SHA2-512 hashes of the same public key) in all signed metadata on their TUF repositories.
References
- The PR fixing this issue is #369.
- The latest TUF specification advises using only SHA2-256 hashes of public keys.
- Commit b383bafd27472310a650f3733e686163a868b71a removed support for clients generating multiple key IDs for the same public key. This commit is older than the first v.0.1.0 tag for go-tuf.
- There is an outstanding issue for removing the non-standard
keyid_hash_algorithmsfield in TUF metadata which arguably led to this issue. - A more robust solution is discussed (but not necessarily recommended) in TAP 12, which suggests deduplicating public keys even more strongly on the basis of the fundamental parameters (e.g., exponents) to the cryptosystem rather than specific encodings (e.g., PEM) of public keys.
For more information
If you have any questions or comments about this advisory:
- Open an issue in go-tuf
- Email us at TUF's mailing list
- The #tuf channel on CNCF Slack.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/theupdateframework/go-tuf | all versions | 0.3.2 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/theupdateframework/go-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 github.com/theupdateframework/go-tuf to 0.3.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-3633-5h82-39pq 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-3633-5h82-39pq 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-3633-5h82-39pq. 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-3633-5h82-39pq in your dependencies?
O3 detects GHSA-3633-5h82-39pq across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.