CVE-2026-42189: Russh: Pre-auth DoS via unbounded allocation in keyboard-interactive auth
Russh is a Rust SSH client & server library. Prior to version 0.60.1, a pre-authentication denial-of-service vulnerability exists in the server's keyboard-interactive authentication handler. A malicious client can crash any russh-based server that implements keyboard-interactive auth (e.g., for 2FA/TOTP) with a single malformed packet, requiring no credentials. This issue has been patched in version 0.60.1.
Affected Software
Remediation
Event History
Frequently Asked Questions
What is the severity of CVE-2026-42189?
CVE-2026-42189 has a severity classification that indicates it can lead to a denial-of-service condition.
How do I fix CVE-2026-42189?
To fix CVE-2026-42189, upgrade to version 0.60.1 or later of the Russh library.
What is the impact of CVE-2026-42189?
The impact of CVE-2026-42189 is that it allows a malicious client to crash the server through unbounded resource allocation.
Which versions of Russh are affected by CVE-2026-42189?
Versions of Russh prior to 0.60.1 are affected by CVE-2026-42189.
When was CVE-2026-42189 reported?
CVE-2026-42189 was reported and acknowledged prior to the release of version 0.60.1.