# GHSA-fhvh-vw7h-9xf3: libcrux-ml-dsa: Signature Verification on AVX2 Platforms Mishandles Edge Case

> Attackers can bypass signature verification in ML-DSA libraries using AVX2 instructions by crafting invalid signatures, requiring an upgrade to fix.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 5 May 2026
- **Also known as:** RUSTSEC-2026-0125

## What is GHSA-fhvh-vw7h-9xf3?

GHSA-fhvh-vw7h-9xf3 is a vulnerability in libcrux-ml-dsa, published on 5 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The AVX2 implementation of ML-DSA verification incorrectly implemented
the `use_hint` function, mishandling an edge case that should lead to
signature rejection.

## Impact
An attacker could make the ML-DSA verifier accept a crafted invalid
signature under a maliciously generated verification key, if the AVX2
implementation is used.

## Mitigation
From version `0.0.9` the edge case is handled correctly and invalid
signatures are rejected.

## Which versions are affected by GHSA-fhvh-vw7h-9xf3?

3 open source packages ship an affected version, including libcrux-ml-dsa.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `libcrux-ml-dsa` | crates.io | All versions | 0.0.9 |
| `libcrux-ml-dsa` | crates.io | All versions | 0.0.9 |
| `libcrux-ml-dsa` | crates.io | From 0.0.0-0 | 0.0.9 |

## How do I fix GHSA-fhvh-vw7h-9xf3?

Upgrade libcrux-ml-dsa to 0.0.9 or later.

## Is GHSA-fhvh-vw7h-9xf3 being exploited?

There is no known exploitation of GHSA-fhvh-vw7h-9xf3 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for GHSA-fhvh-vw7h-9xf3 and fix it if it is affected.

What it is: GHSA-fhvh-vw7h-9xf3 is a vulnerability in libcrux-ml-dsa, published on 5 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of GHSA-fhvh-vw7h-9xf3 in the wild and no public exploit code.

Affected packages and fixed versions:
- libcrux-ml-dsa (crates.io): affected all versions; fixed in 0.0.9
- libcrux-ml-dsa (crates.io): affected all versions; fixed in 0.0.9
- libcrux-ml-dsa (crates.io): affected from 0.0.0-0; fixed in 0.0.9

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/GHSA-fhvh-vw7h-9xf3/ (Markdown: https://insights.sbomify.com/GHSA-fhvh-vw7h-9xf3/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/GHSA-fhvh-vw7h-9xf3

---
From sbomify Insights: https://insights.sbomify.com/GHSA-fhvh-vw7h-9xf3/
Summaries are generated and may contain mistakes; the official description above is the record.