[ CVE-2026-116773 · Published 27 Oct 2026 ]
russh's SSH client is susceptible to unbounded allocations via EXT_INFO packets
[ Why it matters ]Priority signals
- Public proof-of-concept exploit exists (CISA SSVC)
[ Description ]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.
[ Fixes ]Fixes and patches
- russh 0.65Fixed version · GitHub Advisories · rust package russh: upgrade to 0.65 or later (affected < 0.65)
[ Packages ]Affected open-source packages
- russh rustAffected < 0.65 · fixed in 0.65 · GHSA-4p9f-7p9m-5vfg