CVE-2026-102643

AsyncSSH: SFTPServer Chroot Escape

Published Nov 9, 2026 CVSS 3.1 · 8.8 High EPSS < 1% KEV · Not listed
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 2.24.1, SFTPServer.map_path() uses posixpath.normpath() on a client-supplied path and removes only one leading slash before passing the result to posixpath.join() with the configured chroot. An authenticated SFTP user can supply a path beginning with exactly two slash characters, causing POSIX normalization to preserve the double-leading-slash form and the subsequent join to treat the remaining pathname as absolute. This bypasses the SFTP chroot and permits reads and writes with the operating-system permissions of the account running the server, which may enable code execution depending on writable targets. This issue is fixed in version 2.24.1.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

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History
Type Values Removed Values Added
First Time appeared Ronf
Ronf asyncssh
Vendors & Products Ronf
Ronf asyncssh
Type Values Removed Values Added
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 2.24.1, SFTPServer.map_path() uses posixpath.normpath() on a client-supplied path and removes only one leading slash before passing the result to posixpath.join() with the configured chroot. An authenticated SFTP user can supply a path beginning with exactly two slash characters, causing POSIX normalization to preserve the double-leading-slash form and the subsequent join to treat the remaining pathname as absolute. This bypasses the SFTP chroot and permits reads and writes with the operating-system permissions of the account running the server, which may enable code execution depending on writable targets. This issue is fixed in version 2.24.1.
Title AsyncSSH: SFTPServer Chroot Escape
Weaknesses CWE-22
CWE-50
References
Metrics cvssV3_1

{'score': 8.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Nov 9, 2026, 9:51 PM
Reserved
Sep 29, 2026, 3:56 PM
Status
Awaiting Analysis
Published
Nov 9, 2026, 10:18 PM
Modified
Nov 12, 2026, 10:18 PM