PYSEC-2026-3809 asyncssh has an incomplete fix for CVE-2026-45309 — AuthorizedKeysFile %u still escapes the intended directory via a leading ~ (and weakly via ${ENV}) username substitution

Incomplete fix for CVE-2026-45309 GHSA-g794-3fmp-753h. The 2.23.0 guard that sanitises the SSH username before %u substitution in AuthorizedKeysFile blocks /, \ and .., but does not block a leading or $ENV, both of which are re-introduced by later expansion and reach the file open — defeating the...

asyncssh has an incomplete fix for CVE-2026-45309 — AuthorizedKeysFile %u still escapes the intended directory via a leading ~ (and weakly via ${ENV}) username substitution

Incomplete fix for CVE-2026-45309 GHSA-g794-3fmp-753h. The 2.23.0 guard that sanitises the SSH username before %u substitution in AuthorizedKeysFile blocks /, \ and .., but does not block a leading or $ENV, both of which are re-introduced by later expansion and reach the file open — defeating the...

asyncssh has an incomplete fix for CVE-2026-45309 — AuthorizedKeysFile %u still escapes the intended directory via a leading ~ (and weakly via ${ENV}) username substitution

Incomplete fix for CVE-2026-45309 GHSA-g794-3fmp-753h. The 2.23.0 guard that sanitises the SSH username before %u substitution in AuthorizedKeysFile blocks /, \ and .., but does not block a leading or $ENV, both of which are re-introduced by later expansion and reach the file open — defeating the...

GHSA-QR67-GV47-XWWH asyncssh has an incomplete fix for CVE-2026-45309 — AuthorizedKeysFile %u still escapes the intended directory via a leading ~ (and weakly via ${ENV}) username substitution

Incomplete fix for CVE-2026-45309 GHSA-g794-3fmp-753h. The 2.23.0 guard that sanitises the SSH username before %u substitution in AuthorizedKeysFile blocks /, \ and .., but does not block a leading or $ENV, both of which are re-introduced by later expansion and reach the file open — defeating the...

CVE-2026-45309

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 2.23.0, AsyncSSH expands the OpenSSH-compatible AuthorizedKeysFile %u token in asyncssh/config.py, asyncssh/connection.py,...

CVE-2026-45309 AsyncSSH `AuthorizedKeysFile %u` path traversal allows attacker-selected authorized keys to authenticate a traversal username

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 2.23.0, AsyncSSH expands the OpenSSH-compatible AuthorizedKeysFile %u token in asyncssh/config.py, asyncssh/connection.py,...

CVE-2026-45309 AsyncSSH `AuthorizedKeysFile %u` path traversal allows attacker-selected authorized keys to authenticate a traversal username

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 2.23.0, AsyncSSH expands the OpenSSH-compatible AuthorizedKeysFile %u token in asyncssh/config.py, asyncssh/connection.py,...

CVE-2026-45309

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 2.23.0, AsyncSSH expands the OpenSSH-compatible AuthorizedKeysFile %u token in asyncssh/config.py, asyncssh/connection.py,...

CVE-2026-45309: Improper Limitation of a Pathname to a Restricted Directory

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 2.23.0, AsyncSSH expands the OpenSSH-compatible AuthorizedKeysFile %u token in asyncssh/config.py, asyncssh/connection.py,...

CVE-2026-54590

A flaw was found in AsyncSSH, a Python package for implementing the SSHv2 protocol. An incomplete fix for a previous vulnerability allowed an attacker to bypass security restrictions in the AuthorizedKeysFile processing. By using specific characters like or environment variables $ENV in the...

DEBIAN-CVE-2026-54590

AsyncSSH is a Python package which provides an asynchronous client and server implementation of the SSHv2 protocol on top of the Python asyncio framework. Version 2.23.0 contains an incomplete fix for CVE-2026-45309 in SSHServerConfig.settokens that blocks /, , and .. before %u substitution in...

CVE-2026-54590 AsyncSSH AuthorizedKeysFile username substitution bypass through ~ and environment expansion

AsyncSSH is a Python package which provides an asynchronous client and server implementation of the SSHv2 protocol on top of the Python asyncio framework. Version 2.23.0 contains an incomplete fix for CVE-2026-45309 in SSHServerConfig.settokens that blocks /, , and .. before %u substitution in...

CVE-2026-54590 AsyncSSH AuthorizedKeysFile username substitution bypass through ~ and environment expansion

AsyncSSH is a Python package which provides an asynchronous client and server implementation of the SSHv2 protocol on top of the Python asyncio framework. Version 2.23.0 contains an incomplete fix for CVE-2026-45309 in SSHServerConfig.settokens that blocks /, , and .. before %u substitution in...

CVE-2026-54590

AsyncSSH is a Python package which provides an asynchronous client and server implementation of the SSHv2 protocol on top of the Python asyncio framework. Version 2.23.0 contains an incomplete fix for CVE-2026-45309 in SSHServerConfig.settokens that blocks /, , and .. before %u substitution in...

PT-2026-56577

Name of the Vulnerable Software and Affected Versions AsyncSSH version 2.23.0 Description An incomplete fix in the SSHServerConfig. set tokens function fails to block leading or $ENV characters before %u substitution in the AuthorizedKeysFile. This allows subsequent expansion in expand val and...

Directory Traversal

Overview Affected versions of this package are vulnerable to Directory Traversal via the AuthorizedKeysFile %u token. An attacker can gain unauthorized SSH authentication by supplying a specially crafted username containing path traversal sequences, allowing the server to read an...

GHSA-G794-3FMP-753H AsyncSSH `AuthorizedKeysFile %u` path traversal allows attacker-selected authorized keys to authenticate a traversal username

Summary AsyncSSH 2.22.0 expands the OpenSSH-compatible AuthorizedKeysFile %u token with the raw SSH username during pre-authentication server config reload. A server configured with a documented per-user key pattern such as AuthorizedKeysFile authorizedkeys/%u can be made to read an authorized-ke...