ronf AsyncSSH up to 2.22.x AuthorizedKeysFile asyncssh/config.py path traversal

Summaryinfo

A vulnerability classified as problematic has been found in ronf AsyncSSH up to 2.22.x. This affects an unknown part of the file asyncssh/config.py of the component AuthorizedKeysFile Handler. The manipulation leads to path traversal. This vulnerability is documented as CVE-2026-45309. The attack can be initiated remotely. There is not any exploit available.

Detailsinfo

A vulnerability was found in ronf AsyncSSH up to 2.22.x and classified as problematic. This issue affects some unknown processing of the file asyncssh/config.py of the component AuthorizedKeysFile Handler. The manipulation with an unknown input leads to a path traversal vulnerability. Using CWE to declare the problem leads to CWE-22. The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory. Impacted is confidentiality. The summary by CVE is:

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, asyncssh/auth_keys.py, and asyncssh/misc.py with the raw SSH username during pre-authentication server config reload, allowing a server configured with AuthorizedKeysFile authorized_keys/%u to read an authorized-keys file outside the intended directory when the SSH username contains /, \, or .. path traversal segments and authenticate with an attacker-selected key file. This issue is fixed in version 2.23.0.

It is possible to read the advisory at github.com. The identification of this vulnerability is CVE-2026-45309 since 05/11/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. It demands that the victim is doing some kind of user interaction. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1006 according to MITRE ATT&CK.

Upgrading to version 2.23.0 eliminates this vulnerability.

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Productinfo

Vendor

• ronf

Name

• AsyncSSH

Version

• 2.0
• 2.1
• 2.2
• 2.3
• 2.4
• 2.5
• 2.6
• 2.7
• 2.8
• 2.9
• 2.10
• 2.11
• 2.12
• 2.13
• 2.14
• 2.15
• 2.16
• 2.17
• 2.18
• 2.19
• 2.20
• 2.21
• 2.22

Website

• Product: https://github.com/ronf/asyncssh/

CPE 2.3info

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CPE 2.2info

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