High severity · published May 8, 2026
CVE-2026-42189
Russh: Pre-auth DoS via unbounded allocation in keyboard-interactive auth
7.5
CVSS
0.5%
EPSS
No
On KEV
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 vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.5% · higher than 41% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
RU
russh · Eugeny
< 0.60.1 · source: vendor, NVD
WA
Warpgate · Warpgate Project
before 0.23.1 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-42189
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-42189
Patch
https://github.com/Eugeny/russh/commit/6c3c80a9b6d60763d6227d60fa8310e57172a4d1
Product
https://github.com/Eugeny/russh/releases/tag/v0.60.1
Exploit
https://github.com/Eugeny/russh/security/advisories/GHSA-f5v4-2wr6-hqmg
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