CVE-2026-111061 russh agent server converts constraint records into unbounded never-rolled-back tasks
An attacker can exhaust memory and tasks in the russh SSH agent by sending repeated constraint records, causing a denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-111061?
CVE-2026-111061 is a medium-severity denial of service vulnerability in Eugeny russh, published on 19 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
russh is a Rust SSH client and server library that includes an SSH agent protocol implementation. Prior to 0.64.1, the agent server spawns a separate long-lived task for every SSH_AGENT_CONSTRAIN_LIFETIME record in a constrained add-key request. The loop accepts repeated lifetime records, clones the key blob into each task, and does not roll back tasks when later constraint parsing fails. An attacker that can speak the agent protocol locally or through agent forwarding can exhaust memory and tasks until the agent process is starved or terminated, denying SSH agent service. This issue is fixed in version 0.64.1.
Weakness: CWE-770
Which versions are affected by CVE-2026-111061?
2 open source packages ship an affected version, including russh.
| Package | Affected | Fixed in |
|---|---|---|
russh crates.io | All versions | 0.64.1 |
russh crates.io | All versions | 0.64.1 |
How do I fix CVE-2026-111061?
Upgrade russh to 0.64.1 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-2026-111061 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-111061 exists.
Sources
Also known as DEBIAN-CVE-2026-111061, GHSA-4wc5-f2rc-q74m, UBUNTU-CVE-2026-111061.