Infinite loop in AsyncSSH - CVE-2026-62949
Published: October 5, 2026
Vulnerability identifier: #VU153258
CSH Severity: Low
CVSS v4: 7.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-62949
CWE-ID: CWE-835
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote user to cause a denial of service.
The vulnerability exists due to an infinite loop caused by missing lower-bound validation in AsyncSSH channel handling when processing an SSH channel open message with a maximum packet size of zero. A remote user can send a crafted SSH channel open message to cause a denial of service.
On affected servers, a single malicious channel can freeze all current and future connections.
Affected software
AsyncSSH
How to mitigate CVE-2026-62949
Install security update from vendor's website.
AsyncSSH - update to 2.24.0