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Fencer Vulns
high 7.5

CVE-2026-45309 json

AsyncSSH `AuthorizedKeysFile %u` path traversal allows attacker-selected authorized keys to authenticate a traversal username

published 2026-05-27 5 mo ago modified 2026-10-24 15 d ago also EUVD-2026-45255 , GHSA-g794-3fmp-753h , PYSEC-2026-2384

cvss
7.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 48%
public exploits
0
none known

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.

Patch / fix

  • pypi asyncssh 2.23.0
  • asyncssh_project asyncssh 2.23.0
  • python-asyncssh Debian 14 2.23.0-1

debian advisories DEBIAN-CVE-2026-45309

  • python-asyncssh openSUSE Tumbleweed 2.23.1-1.1

opensuse advisories openSUSE-SU-2026:11042-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-45309 updated cvss 5.9

asyncssh: AsyncSSH: Authentication bypass due to path traversal in username during pre-authentication

  • Red Hat Ceph Storage 7 rhceph/rhceph-7-rhel9 Red Hat Ceph Storage 8 rhceph/rhceph-8-rhel9 Red Hat Ceph Storage 9 rhceph/rhceph-9-rhel9
    affected: no fix available “Fix deferred”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
partial
Assessed
3 mo ago

Exploit prediction

0.59% chance of exploitation in the next 30 days, higher than 48% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/ronf/asyncssh/security/advisories/GHSA-g794-3fmp-753h referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 8.2 CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
CNA 4.0 8.2 CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Affected packages

ecosystem package affected fixed in
pypi asyncssh
>=2.22.0, <2.23.0
2.23.0

Affected products

  • ronf asyncssh

Classification

Weakness
  • CWE-22 Improper Limitation of a Pathname to a Restricted Directory

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.