CVE-2026-116773 russh's SSH client is susceptible to unbounded allocations via EXT_INFO packets
- Exploited in the wild
- Not known
- Fix
- None listed
What is CVE-2026-116773?
CVE-2026-116773 is a medium-severity vulnerability in Eugeny russh, published on 27 Oct 2026.
Official description
russh is a Rust SSH client and server library that includes an SSH agent protocol implementation. Prior to 0.65.0, the client Session::process_packet path in russh/src/client/encrypted.rs accepts repeated packets encoded with russh's private msg::EXT_INFO = 7 before authentication, while the standards-compliant EXT_INFO message number 82 does not reach the affected handler. The handle_ext_info function appends every parsed extension name to received_extensions without clearing, deduplicating, or bounding the vector. A malicious SSH server that deliberately sends private message number 7 can therefore retain an unbounded number of attacker-controlled extension names for the session lifetime, causing progressive client memory exhaustion. This issue is fixed in version 0.65.0.
Weakness: CWE-770
Which versions are affected by CVE-2026-116773?
How do I fix CVE-2026-116773?
No fix has been published for CVE-2026-116773 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-116773 being exploited?
There is no known exploitation of CVE-2026-116773 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-116773, GHSA-4p9f-7p9m-5vfg, UBUNTU-CVE-2026-116773.