CVE-2026-102822 russh: negotiating a MAC-requiring block cipher (CTR/CBC) with mac=none causes a slice-index-out-of-range panic
A remote attacker can cause a denial of service in the russh library by negotiating a MAC-less connection with a MAC-requiring cipher, triggering a panic.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-102822?
CVE-2026-102822 is a low-severity denial of service vulnerability in Eugeny russh, published on 29 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Russh is a Rust SSH client and server library. Prior to 0.63.1, a connection configured to permit mac=none can negotiate it with a MAC-requiring CTR or CBC block cipher because the selection logic validates needs_mac() only when MAC selection fails. A remote peer can then send a packet with a decrypted length of zero, causing russh/src/cipher/mod.rs to shrink the previously read block before indexing buffer.buffer[16..], which panics and terminates the connection task. This issue is fixed in version 0.63.1.
Weakness: CWE-129
Which versions are affected by CVE-2026-102822?
2 open source packages ship an affected version, including russh.
| Package | Affected | Fixed in |
|---|---|---|
russh crates.io | All versions | 0.63.1 |
russh crates.io | All versions | 0.63.1 |
How do I fix CVE-2026-102822?
Upgrade russh to 0.63.1 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 CVE-2026-102822 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-102822 exists.
Sources
Also known as DEBIAN-CVE-2026-102822, GHSA-p8qx-h547-fjw9, UBUNTU-CVE-2026-102822.