GHSA-hc3c-63hc-2r9f Potential Panic on Overlong Ciphertext Buffer
An attacker can cause a denial of service by providing an overlong ciphertext buffer to the libcrux encryption functions, crashing the application.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is GHSA-hc3c-63hc-2r9f?
GHSA-hc3c-63hc-2r9f is a denial of service vulnerability in libcrux-chacha20poly1305, published on 29 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
An application that passes in a ciphertext buffer of length greater
than ptxt.len() + TAG_LEN to libcrux_chacha20poly1305::encrypt or
libcrux_chacha20poly1305::xchacha20_poly1305::encrypt would
experience a panic.
Impact
An application where the length of the ciphertext buffer is under attacker control could be made to crash.
Mitigation
The fix makes it so that libcrux_chacha20poly1305::encrypt and
libcrux_chacha20poly1305::xchacha20_poly1305::encrypt no longer
panic in this case, but instead write out the ciphertext and tag into
the first ptxt.len() + TAG_LEN bytes of the provided buffer.
Which versions are affected by GHSA-hc3c-63hc-2r9f?
3 open source packages ship an affected version, including libcrux-chacha20poly1305.
| Package | Affected | Fixed in |
|---|---|---|
libcrux-chacha20poly1305 crates.io | All versions | 0.0.8 |
libcrux-chacha20poly1305 crates.io | All versions | 0.0.8 |
libcrux-chacha20poly1305 crates.io | From 0.0.0-0 | 0.0.8 |
How do I fix GHSA-hc3c-63hc-2r9f?
Upgrade libcrux-chacha20poly1305 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-hc3c-63hc-2r9f being exploited?
There is no known exploitation of GHSA-hc3c-63hc-2r9f in the wild and no public exploit code.
Sources
Also known as RUSTSEC-2026-0124.