CVE-2026-48108 MEDIUM

CVE-2026-48108: Russh: SSH identification parsing accepted non-canonical client banners and did not bound pre-banner input

Vendor Eugeny
Product russh
Weakness CWE-20 · Input validation
Published June 10, 2026
Last update June 11, 2026

CVSS base score

5.3/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Confidentiality None
Integrity None

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

What the vulnerability does

01Description

Russh is a Rust SSH client & server library. From version 0.34.0-beta.1 to before version 0.61.0, russh did not enforce the SSH identification-string rules as deliberately as OpenSSH. In particular, the server-side identification reader used the same permissive path as the client, allowing pre-banner lines from clients, and the reader did not enforce a bounded number of pre-banner lines. For a library server built on russh, this could allow a remote peer to hold connection setup resources in the cleartext pre-authentication phase with malformed identification input that should have been rejected early. This issue has been patched in version 0.61.0.

Key dates

02Disclosure timeline

June 10, 2026 CVE published
June 11, 2026 Record updated