Summary
libcrux has an Incorrect Check of Signer Response Norm During Verification
The ML-DSA verification algorithm as specified in FIPS 204, subsection 6.3 requires verifiers to check that the infinity norm of the deserialized signer response $z$ does not exceed $\gamma_1 - \beta$ (line 13 of Algorithm 8). The same check is required to be performed during signature generation.
libcrux-ml-dsa did not perform this check correctly during signature verification, accepting signatures with signer response norm above the allowed maximum value. The check is correctly performed during signing.
Mitigation
Starting from version 0.0.8, signature verification uses the correct value for $\gamma_1$ in the signer response norm check.
Impact
Applications using libcrux-ml-dsa for signature verification would have accepted signatures that would be rejected by a conforming implementation.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
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Frequently Asked Questions
- What is GHSA-CP57-FQ8G-QH6V? GHSA-CP57-FQ8G-QH6V is a high-severity security vulnerability in libcrux-ml-dsa (rust), affecting versions < 0.0.8. It is fixed in 0.0.8.
- Which versions of libcrux-ml-dsa are affected by GHSA-CP57-FQ8G-QH6V? libcrux-ml-dsa (rust) versions < 0.0.8 is affected.
- Is there a fix for GHSA-CP57-FQ8G-QH6V? Yes. GHSA-CP57-FQ8G-QH6V is fixed in 0.0.8. Upgrade to this version or later.
- Is GHSA-CP57-FQ8G-QH6V exploitable, and should I be worried? Whether GHSA-CP57-FQ8G-QH6V 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
- What actually determines whether GHSA-CP57-FQ8G-QH6V 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.
- How do I fix GHSA-CP57-FQ8G-QH6V? Upgrade
libcrux-ml-dsato 0.0.8 or later.