CVE-2026-42189

Description

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.

CVSS v3.1 Score

7.5

HIGH

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

EPSS — Exploit Prediction

0.0019

Probability of exploitation

0.40%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-770 CWE-770

CWE-789 CWE-789

Affected Products

Vendor	Product	Versions
russh_project	russh	< 0.60.1
warpgate_project	warpgate	< 0.23.1

References

Advisories & Patches

https://github.com/Eugeny/russh/commit/6c3c80a9b6d60763d6227d60fa8310e57172a4d1 https://github.com/Eugeny/russh/security/advisories/GHSA-f5v4-2wr6-hqmg https://github.com/Eugeny/russh/security/advisories/GHSA-f5v4-2wr6-hqmg

Exploits

https://github.com/Eugeny/russh/security/advisories/GHSA-f5v4-2wr6-hqmg https://github.com/Eugeny/russh/security/advisories/GHSA-f5v4-2wr6-hqmg

Other References

https://github.com/Eugeny/russh/releases/tag/v0.60.1

Frequently Asked Questions

What is 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. It has a CVSS v3.1 base score of 7.5 (HIGH).

How severe is CVE-2026-42189? +

CVE-2026-42189 has a CVSS v3.1 score of 7.5 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0019, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-42189? +

CVE-2026-42189 affects products from russh_project, warpgate_project, specifically: russh, warpgate. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-42189? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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