What’s Vulnerable › Vulnerabilities

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

• Severity: medium (CVSS 5.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-06-10 · updated 2026-07-23
• Weakness: CWE-20

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.

Affected products

• Eugeny russh: from 0.34.0-beta.1, < 0.61.0

References

• https://github.com/Eugeny/russh/security/advisories/GHSA-76r6-x97p-67vr
• https://github.com/Eugeny/russh/security/advisories/GHSA-76r6-x97p-67vr

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