CVE-2026-54591: Ronf Asyncssh

High severity, CVSS 8.1. EPSS: 0.5% chance of exploitation in the next 30 days.

AsyncSSH is a Python package which provides an asynchronous client and server implementation of the SSHv2 protocol on top of the Python asyncio framework. Prior to 2.23.1, a malicious SSH server can write arbitrary files on the asyncssh SCP client's filesystem by sending filenames containing ../ traversal sequences because _parse_cd_args in scp.py returns server-provided names verbatim and _recv_files joins them to the destination path without enforcing the target directory boundary. This issue is fixed in version 2.23.1.

Affected products

• Ronf Asyncssh: before 2.23.1 (fixed in 2.23.1)

Published 2026-07-08. Last modified 2026-07-10.