Medium [CVE-2026-45309] Authentication bypass due to path traversal in username during pre-authentication
This medium-severity Red Hat Linux advisory covers CVE-2026-45309 affecting Red Hat Ceph Storage 7, Red Hat Ceph Storage 8, Red Hat Ceph Storage 9.
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Summary
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. This allows the attacker to read sensitive authorized-keys files from unintended directories, potentially leading to unauthorized authentication and system access.
Red Hat rates this vulnerability as Moderate rather than the upstream HIGH severity because exploitation requires the AsyncSSH server to be specifically configured with AuthorizedKeysFile %u, a non-default setting that is not commonly deployed in Red Hat environments.
Affected products named by the advisory: Red Hat Ceph Storage 7; Red Hat Ceph Storage 8; Red Hat Ceph Storage 9.
- < 2.23.0
Official advisory · high-confidence parse· fetched 1 month ago·verify at source
Mitigation
Upgrade to a fixed release: 2.23.0. That is the remediation for this advisory.
The vendor advisory may list interim mitigations or workarounds not captured here. Review it before change work.
Official advisory · high-confidence parse· fetched 1 month ago·verify at source
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