GHSA-75rw-34q6-72cr
CRITICALGHSA-75rw-34q6-72cr is a critical-severity (CVSS 9.8) CWE-347 vulnerability in biscuit-auth. 2 public exploit references exist, so weaponization risk is real. O3 Security confirms whether GHSA-75rw-34q6-72cr is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Signature forgery in Biscuit
Blast Radius
biscuit-auth🐹github.com/biscuit-auth/biscuit-go☕com.clever-cloud:biscuit-javaReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects crates.io, Go, Maven packages — download data is not available via public APIs for these ecosystems.
Description
Impact
The paper Cryptanalysis of Aggregate Γ-Signature and Practical Countermeasures in Application to Bitcoin defines a way to forge valid Γ-signatures, an algorithm that is used in the Biscuit specification version 1. It would allow an attacker to create a token with any access level.
As Biscuit v1 was still an early version and not broadly deployed, we were able to contact all known users of Biscuit v1 and help them migrate to Biscuit v2. We are not aware of any active exploitation of this vulnerability.
Patches
The version 2 of the specification mandates a different algorithm than gamma signatures and as such is not affected by this vulnerability. The Biscuit implementations in Rust, Haskell, Go, Java and Javascript all have published versions following the v2 specification.
Workarounds
There is no known workaround, any use of Biscuit v1 should be migrated to v2.
References
Cryptanalysis of Aggregate Γ-Signature and Practical Countermeasures in Application to Bitcoin
For more information
If you have any questions or comments about this advisory:
- Open an issue in biscuit-auth/biscuit
- Ask questions on Matrix
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | biscuit-auth | ≥ 1.0.0&&< 2.0.0 | 2.0.0 |
| 🐹Go | github.com/biscuit-auth/biscuit-go | all versions | 2.0.0 |
| ☕Maven | com.clever-cloud:biscuit-java | all versions | 2.0.0 |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for biscuit-auth. 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 biscuit-auth to 2.0.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-75rw-34q6-72cr 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-75rw-34q6-72cr 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-75rw-34q6-72cr. 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-75rw-34q6-72cr in your dependencies?
O3 detects GHSA-75rw-34q6-72cr across crates.io, Go, Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.