CVE-2026-54590

Name	CVE-2026-54590
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.
Source	CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
Debian Bugs	1141817

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
python-asyncssh (PTS)	bullseye	2.5.0-0.1	vulnerable
	bullseye (security)	2.5.0-0.1+deb11u1	vulnerable
	bookworm	2.10.1-2+deb12u2	vulnerable
	bookworm (security)	2.10.1-2+deb12u1	vulnerable
	trixie	2.20.0-1	fixed
	forky, sid	2.23.0-1	vulnerable

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
python-asyncssh	source	trixie	(not affected)
python-asyncssh	source	(unstable)	(unfixed)			1141817

Notes

[trixie] - python-asyncssh <not-affected> (Incomplete fix for CVE-2026-45309 not applied)
https://github.com/ronf/asyncssh/security/advisories/GHSA-qr67-gv47-xwwh
Fixed by: https://github.com/ronf/asyncssh/commit/3d515ba9ba0cd9990d248bdf62bcf05d51261a88 (v2.23.1)