CVE-2026-48108: CWE-20: Improper Input Validation in Eugeny russh
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.
AI Analysis
Technical Summary
CVE-2026-48108 concerns an improper input validation vulnerability (CWE-20) in the russh library, affecting versions >=0.34.0-beta.1 and <0.61.0. The vulnerability arises because the server-side identification reader does not strictly enforce SSH identification-string rules, permitting multiple pre-banner lines and failing to bound their number. This can allow a remote attacker to hold connection setup resources during the cleartext pre-authentication phase by sending malformed identification input that should have been rejected early. The vulnerability was addressed and patched in russh version 0.61.0.
Potential Impact
The vulnerability does not affect confidentiality or integrity but can cause resource exhaustion on the server during the SSH connection setup phase. This may lead to denial of service by holding connection setup resources with malformed identification input. There are no known exploits in the wild.
Mitigation Recommendations
A fix is available in russh version 0.61.0. Users and developers should upgrade to version 0.61.0 or later to remediate this issue. No other official remediation guidance is provided. Patch status is confirmed by the vendor's versioning information.
CVE-2026-48108: CWE-20: Improper Input Validation in Eugeny russh
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.
CVSS v3.1
Score 5.3medium
Affected software
pkg:cargo/github/Eugeny/russhRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-48108 concerns an improper input validation vulnerability (CWE-20) in the russh library, affecting versions >=0.34.0-beta.1 and <0.61.0. The vulnerability arises because the server-side identification reader does not strictly enforce SSH identification-string rules, permitting multiple pre-banner lines and failing to bound their number. This can allow a remote attacker to hold connection setup resources during the cleartext pre-authentication phase by sending malformed identification input that should have been rejected early. The vulnerability was addressed and patched in russh version 0.61.0.
Potential Impact
The vulnerability does not affect confidentiality or integrity but can cause resource exhaustion on the server during the SSH connection setup phase. This may lead to denial of service by holding connection setup resources with malformed identification input. There are no known exploits in the wild.
Mitigation Recommendations
A fix is available in russh version 0.61.0. Users and developers should upgrade to version 0.61.0 or later to remediate this issue. No other official remediation guidance is provided. Patch status is confirmed by the vendor's versioning information.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-05-20T18:46:58.287Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a29d0250e53e73883986cd8
Added to database: 6/10/2026, 8:59:17 PM
Last enriched: 6/10/2026, 9:15:04 PM
Last updated: 6/10/2026, 10:37:29 PM
Views: 8
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