Russh: Configured server auth-attempt cap is not enforced in the USERAUTH_REQUEST runtime path

[ 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. Prior to 0.62.6, the USERAUTH_REQUEST path reached from server::run_stream in russh/src/server/encrypted.rs increments self.common.auth_attempts but never compares it with server::Config.max_auth_attempts. An unauthenticated remote client can continue submitting authentication requests on one connection beyond the configured cap, bypassing the deployment's attempt-limiting policy and increasing online guessing opportunity and backend authentication workload. This issue is fixed in version 0.62.6.

[ Fixes ]Fixes and patches

• russh 0.62.6Fixed version · GitHub Advisories · rust package russh: upgrade to 0.62.6 or later (affected <= 0.62.5)

[ Packages ]Affected open-source packages

• russh rustAffected <= 0.62.5 · fixed in 0.62.6 · GHSA-g6xm-f9xp-qq35

[ References ]References

• github.com/Eugeny/russh/commit/f8fd0b11a393364dc7f01a182482d86adafdd653
• github.com/Eugeny/russh/releases/tag/v0.62.6
• github.com/Eugeny/russh/security/advisories/GHSA-g6xm-f9xp-qq35