CVE-2026-48108: 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 ...

Description

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.

Metrics

CVSS 3.1

5.3/10

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

EPSS Probability

0.28%

19.4th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-20

References

Timeline

Published: Jun 10, 2026
Last Modified: Jun 17, 2026
Status: Deferred

Frequently Asked Questions

What is CVE-2026-48108?

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.

How severe is CVE-2026-48108?

CVE-2026-48108 has a CVSS score of 5.3/10 (MEDIUM severity). The EPSS model estimates a 0.28% probability of exploitation in the next 30 days.

How do I fix CVE-2026-48108?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.