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CVE-2026-45309— AsyncSSH `AuthorizedKeysFile %u` path traversal allows attacker-selected authorized keys to authenticate a traversal username

Quick assessment

Affected
ronf asyncssh
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Ron Frederick AsyncSSH是Ron Frederick个人开发者的一款异步SSH协议库。 Ron Frederick AsyncSSH 2.23.0之前版本存在路径遍历漏洞，该漏洞源于在预认证服务器配置重载过程中扩展OpenSSH兼容的AuthorizedKeysFile %u令牌时未正确清理路径，允许包含路径遍历片段的SSH用户名读取预期目录之外的授权密钥文件并使用攻击者选择的密钥文件进行认证。

AI Predicted 7.5 Difficulty: Easy EPSS 0.59% · P48

Possible ATT&CK Techniques 1 AI

T1078 · Valid Accounts

Affected Version Matrix 1

VendorProduct Version RangeStatus
ronf asyncssh < 2.23.0 affected
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I. Basic Information for CVE-2026-45309

Vulnerability Information
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Vulnerability Title
AsyncSSH `AuthorizedKeysFile %u` path traversal allows attacker-selected authorized keys to authenticate a traversal username
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
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
Source: CVE Program / CVE List V5
Vulnerability Type
对路径名的限制不恰当(路径遍历)
Source: CVE Program / CVE List V5
Vulnerability Title
Ron Frederick AsyncSSH 路径遍历漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Ron Frederick AsyncSSH是Ron Frederick个人开发者的一款异步SSH协议库。 Ron Frederick AsyncSSH 2.23.0之前版本存在路径遍历漏洞，该漏洞源于在预认证服务器配置重载过程中扩展OpenSSH兼容的AuthorizedKeysFile %u令牌时未正确清理路径，允许包含路径遍历片段的SSH用户名读取预期目录之外的授权密钥文件并使用攻击者选择的密钥文件进行认证。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
ronf asyncssh < 2.23.0 -

II. Public POCs for CVE-2026-45309

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III. Intelligence Information for CVE-2026-45309

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Patches & Fixes for CVE-2026-45309 (2)

Vendor Advisories for CVE-2026-45309 (1)

IV. Related Vulnerabilities

Same product: asyncssh
Same vendor: ronf
Same weakness: CWE-22

V. Comments for CVE-2026-45309

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