Bug 2569600 (CVE-2026-77473)

Summary: CVE-2026-77473 asyncssh: AsyncSSH: Arbitrary file write via path traversal in SFTP client
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
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Priority: medium    
Version: unspecifiedKeywords: Security
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OS: Linux   
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A flaw was found in AsyncSSH. A malicious or compromised SFTP (SSH File Transfer Protocol) server can exploit path traversal sequences during recursive remote-to-local file transfers to write arbitrary files to the client system. Because the client trusts server-supplied filenames without proper validation, the destination path can escape the intended target directory and create or overwrite files anywhere the client process has write permissions.
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Description OSIDB Bzimport 2026-11-10 13:10:36 UTC 
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 2.24.1, recursive remote-to-local SFTP copies in SFTPClient._copy() in asyncssh/sftp.py, reached through get(), mget(), and copy(), trust filenames returned by a remote server's directory enumeration. A malicious or compromised SFTP server can return an absolute filename or a filename containing path separators and parent-directory traversal, causing destination path construction to escape the requested local directory and write attacker-selected content to locations writable by the client process. This issue is fixed in version 2.24.1.