CVE-2026-111062

Description

russh is a Rust SSH client and server library. From version 0.34.0-beta.1 until version 0.64.0, its SSH server does not require the signature algorithm in a public-key authentication signature to match the algorithm named in the authentication request. A client possessing an authorized RSA private key can announce  rsa-sha2-512  while supplying a valid  ssh-rsa  SHA-1 signature, bypassing restrictions or producing misleading audit records when applications rely on the requested algorithm. A valid private-key signature remains required, and russh clients are not affected. This issue is fixed in version 0.64.0.

References

• https://github.com/Eugeny/russh/commit/a0ded76bdc352f8fbeaaeb175fb2a0c586fbc8f2
• https://github.com/Eugeny/russh/pull/759
• https://github.com/Eugeny/russh/releases/tag/v0.64.0
• https://github.com/Eugeny/russh/security/advisories/GHSA-j7h2-66j4-ghjf
• https://github.com/Eugeny/russh/security/advisories/GHSA-j7h2-66j4-ghjf