# CVE-2026-102643: AsyncSSH: SFTPServer Chroot Escape

Status: published. Published: 2026-11-09. Updated: 2026-11-09.

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 remediation reported in collected sources

## Affected products and versions

- ronf / asyncssh: < 2.24.1 (affected). Source: CNA: GitHub_M

## Severity and prioritization

- CVSS 3.1: 8.8 (high); CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H; source: CNA: GitHub_M

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: CWE-22, CWE-50

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/ronf/asyncssh/security/advisories/GHSA-w29m-45fc-22v9 (CNA: GitHub_M; x_refsource_CONFIRM)

- https://github.com/ronf/asyncssh/commit/d4fc430d37b234cb35f1ba2cca834b2dbe1302cf (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/ronf/asyncssh/releases/tag/v2.24.1 (CNA: GitHub_M; x_refsource_MISC)

## Provenance

- CNA: GitHub_M: https://www.cve.org/CVERecord?id=CVE-2026-102643; retrieved 2026-11-09; source updated 2026-11-09

Revision: 458900267350ea32c82f0183054531a53e7e9b86e9e8649e6233d29341723fac

Canonical: https://y2.dev/cve/CVE-2026-102643

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