CVE-2026-102824 Russh: Missing X25519 zero-point validation in hybrid ML-KEM key exchange
A malicious SSH peer can force the X25519 contribution to zero in hybrid key exchange, weakening cryptographic fallback protection in the Russh library.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-102824?
CVE-2026-102824 is a medium-severity vulnerability in Eugeny russh, published on 29 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
Russh is a Rust SSH client and server library. Prior to 0.63.0, the hybrid ML-KEM 768 and X25519 implementation in russh/src/kex/hybrid_mlkem.rs accepts an all-zero 32-byte peer X25519 public key in both server_dh and compute_shared_secret, forcing the X25519 contribution to the combined shared secret to zero. A malicious SSH peer can therefore make the combined secret depend only on ML-KEM, defeating the hybrid exchange's intended fallback protection if ML-KEM is later weakened. This issue is fixed in version 0.63.0.
Weakness: CWE-327
Which versions are affected by CVE-2026-102824?
2 open source packages ship an affected version, including russh.
| Package | Affected | Fixed in |
|---|---|---|
russh crates.io | All versions | 0.63.0 |
russh crates.io | All versions | 0.63.0 |
How do I fix CVE-2026-102824?
Upgrade russh to 0.63.0 or later.
Is CVE-2026-102824 being exploited?
There is no known exploitation of CVE-2026-102824 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-102824, GHSA-w3jg-pjxf-73p4, UBUNTU-CVE-2026-102824.