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CVE-2026-45309

Asyncssh path traversal

7.5 HIGHPublic exploitEPSS 0.59%
  1. Published17 Jul 2026

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. 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.

CVSS 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
ScopeUnchanged
ConfidentialityNone
IntegrityHigh
AvailabilityNone
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Affected products

Asyncssh< 2.23.0

Remediation

Fixed in
Asyncssh≥ 2.23.0

References

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Frequently asked

Is CVE-2026-45309 being actively exploited?

CVE-2026-45309 is not in the CISA KEV catalog. A public exploit reference exists, so treat it as exploitable. Its EPSS exploit probability is 0.59%.

How severe is CVE-2026-45309?

CVE-2026-45309 has a CVSS 3.1 base score of 7.5, rated high. EPSS estimates a 0.59% probability of exploitation.

Which products are affected by CVE-2026-45309?

Affected products include Asyncssh.

How do I fix CVE-2026-45309?

Upgrade affected software to a fixed version, for example Asyncssh 2.23.0 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.