What is CVE-2026-42189?

CVE-2026-42189 is a high-severity vulnerability in Eugeny Russh, classified under Allocation of Resources Without Limits or Throttling. CVSS score: 7.5/10. Published 2026-05-08.

How severe is CVE-2026-42189?

High severity. CVSS v3 base score is 7.5 out of 10.

Resource exhaustion in Eugeny Russh

CVE-2026-42189

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.

Published 2026-05-08 · last modified 2026-10-26.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.005 (41.5th percentile), scored 2026-11-02.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 41st percentile — 41.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.008 · newest: 0.005 · change: -0.003

Affected products

Weakness classification (CWE)

References

github.com/Eugeny/russh/security/advisories/GHSA-f5v4-2wr6-hqmg (Exploit, Mitigation, Vendor Advisory)
github.com/Eugeny/russh/commit/6c3c80a9b6d60763d6227d60fa8310e57172a4d1 (Patch)
github.com/Eugeny/russh/releases/tag/v0.60.1 (Product, Release Notes)

Frequently asked questions

What is CVE-2026-42189?: CVE-2026-42189 is a high-severity vulnerability in Eugeny Russh, classified under Allocation of Resources Without Limits or Throttling. CVSS score: 7.5/10. Published 2026-05-08.
How severe is CVE-2026-42189?: High severity. CVSS v3 base score is 7.5 out of 10.