CVE-2026-54590 Details
Description
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.
A vulnerability exists in AsyncSSH version 2.23.0, allowing unauthorized access through the AuthorizedKeysFile directive. The issue arises because the version's fix for a previous vulnerability (CVE-2026-45309) was incomplete. While the update blocked certain unsafe characters in usernames, it failed to address leading tildes and environment variable references, which can be exploited to access files outside the intended directory. This vulnerability is present in the SSH server configuration, where the AuthorizedKeysFile directive is set to include user-specific paths.
Users can upgrade to AsyncSSH version 2.23.1, which addresses this vulnerability by properly blocking leading tildes and environment variable references in usernames before they are processed by the AuthorizedKeysFile directive.
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed Jul 8, 2026CISA-ADP
Assessed Jul 10, 2026References to Advisories, Solutions, and Tools
By selecting these links, you will be leaving this site. These are references gathered from the official CVE record and are not endorsed by Volerion.
| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/ronf/asyncssh/security/advisories/GHSA-qr67-gv47-xwwh | CISA-ADP | AdvisoryExploitRemedyVendor |
| https://github.com/ronf/asyncssh/commit/3d515ba9ba0cd9990d248bdf62bcf05d51261a88 | [email protected] | Source CodeVendor |
| https://github.com/ronf/asyncssh/releases/tag/v2.23.1 | [email protected] | Release NotesVendor |
| https://github.com/ronf/asyncssh/security/advisories/GHSA-qr67-gv47-xwwh | [email protected] | AdvisoryExploitRemedyVendor |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-22 | Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') | [email protected] |
| CWE-639 | Authorization Bypass Through User-Controlled Key | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| AsyncSSH | <= 2.23.0 (semver) |
CPE
Remediation
| |
Change History
2 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jul 10, 2026 | CVE Modified | CISA-ADP |
| Jul 8, 2026 | New CVE Received | [email protected] |