CVE-2026-54590
AsyncSSH AuthorizedKeysFile username substitution bypass through ~ and environment expansion
CVSS Score
5.9
EPSS Score
0.3%
EPSS Percentile
20th
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._set_tokens that blocks /, , and .. before %u substitution in AuthorizedKeysFile but does not block a leading ~ or ${ENV}, allowing later expansion in _expand_val and Path(filename).expanduser() to escape the intended authorized-keys directory. This issue is fixed in version 2.23.1.
| CWE | CWE-22 CWE-639 |
| Vendor | ronf |
| Product | asyncssh |
| Published | Jul 8, 2026 |
| Last Updated | Jul 10, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None
Affected Versions
ronf / asyncssh
< 2.23.1