GHSA-xrf2-5r3p-5wgj libcrux: Panic in Signature Hint Decoding During Verification
A manipulated invalid hint in ML-DSA verification causes an out-of-bounds memory access and runtime panic, leading to denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is GHSA-xrf2-5r3p-5wgj?
GHSA-xrf2-5r3p-5wgj is a denial of service vulnerability in libcrux-ml-dsa, published on 4 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
During ML-DSA verification the serialized hint values are decoded as specified in algorithm 22 HintBitUnpack of FIPS 204, subsection 7.1. The algorithm requires that the cumulative hint counters per row of the hint vector are strictly increasing and below a maximum value which depends on the choice of ML-DSA parameter set (line 4).
In libcrux-ml-dsa, hint decoding did not check the boundedness of the cumulative hint counter of the last row of the hint vector.
Impact
A manipulated invalid hint can cause an out-of-bounds memory access since the hint decoding logic may attempt to read outside the bounds of the serialized signature, causing a runtime panic.
Mitigation
Starting from version 0.0.8, hint decoding will check the cumulative hint counter of the last row as well.
Which versions are affected by GHSA-xrf2-5r3p-5wgj?
3 open source packages ship an affected version, including libcrux-ml-dsa.
| Package | Affected | Fixed in |
|---|---|---|
libcrux-ml-dsa crates.io | All versions | 0.0.8 |
libcrux-ml-dsa crates.io | All versions | 0.0.8 |
libcrux-ml-dsa crates.io | From 0.0.0-0 | 0.0.8 |
How do I fix GHSA-xrf2-5r3p-5wgj?
Upgrade libcrux-ml-dsa to 0.0.8 or later.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is GHSA-xrf2-5r3p-5wgj being exploited?
There is no known exploitation of GHSA-xrf2-5r3p-5wgj in the wild and no public exploit code.
Sources
Also known as RUSTSEC-2026-0076.