Vulnerability · Published Oct 27, 2026 · Assigned by GitHub_M

CVE-2026-116696russh's SSH agent server is susceptible to unbound allocations via repeated SSH_AGENT_CONSTRAIN_CONFIRM messages

Low 3.3

In plain English

A low-severity resource allocation without limits in russh from Eugeny. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.1% (higher than 1% of all known vulnerabilities).

Severity (CVSS 3.1)3.3Low

Exploit odds (30 days)0.1%top 98.7% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official description

russh is a Rust SSH client and server library that includes an SSH agent protocol implementation. Prior to 0.65.0, russh::keys::agent::server::serve in russh/src/keys/agent/server.rs accepts repeated SSH_AGENT_CONSTRAIN_CONFIRM records while adding a key and appends every Constraint::Confirm record to the key's retained constraint vector without a count or memory limit. A process that can connect to the agent socket, including the remote side of a forwarded agent session, can repeatedly add constrained keys and cause renewable memory growth that persists for the process lifetime because keys without a lifetime constraint do not expire. This issue is fixed in version 0.65.0.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Debian:14	rust-russh	no fix listed	DEBIAN-CVE-2026-116696
Ubuntu:26.10	rust-russh	no fix listed	UBUNTU-CVE-2026-116696

Affected products (as reported)

Vendor	Product	Versions
Eugeny	russh	< 0.65.0

Weakness: CWE-770 · Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L

References

https://github.com/Eugeny/russh/security/advisories/GHSA-9wfm-jcj8-jfv9 x_refsource_CONFIRM
https://github.com/Eugeny/russh/commit/23aa5d28fe9601c5bdfe9e60b7ec5d4f882c3de6 x_refsource_MISC
https://github.com/Eugeny/russh/releases/tag/v0.65.0 x_refsource_MISC