medium5.9
CVE-2026-54590
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
Impact
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.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| pip | asyncssh | <= 2.23.0 | 2.23.1 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/advisories/GHSA-qr67-gv47-xwwh
- https://github.com/ronf/asyncssh/security/advisories/GHSA-qr67-gv47-xwwh
- https://nvd.nist.gov/vuln/detail/CVE-2026-54590
- https://github.com/ronf/asyncssh/commit/3d515ba9ba0cd9990d248bdf62bcf05d51261a88
- https://github.com/ronf/asyncssh/releases/tag/v2.23.1