CVE-2026-48108

CVE-2026-48108 is a medium-severity vulnerability with a CVSS 3.x base score of 5.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-20.

Key facts

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.

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 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.
Is CVE-2026-48108 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (19th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-48108?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-48108 have an EU (EUVD) identifier?
Yes. CVE-2026-48108 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-36130.
When was CVE-2026-48108 published?
CVE-2026-48108 was published on 2026-06-10 and last updated on 2026-06-17.

References

Other CWE-20 (Improper Input Validation) vulnerabilities

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