AsyncSSH: SFTPServer Chroot Escape

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-102643
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-11-09 22:18:21 UTC
Updated2026-11-14 03:17:22 UTC
DescriptionAsyncSSH 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.

Risk And Classification

Primary CVSS: v3.1 8.8 HIGH from [email protected]

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS: 0.008440000 probability, percentile 0.585060000 (date 2026-11-13)

Problem Types: CWE-22 | CWE-50 | CWE-22 CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') | CWE-50 CWE-50: Path Equivalence: '//multiple/leading/slash'

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary8.8HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED8.8HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Ronf Asyncssh affected < 2.24.1 Not specified

References

ReferenceSourceLinkTags
github.com/ronf/asyncssh/commit/d4fc430d37b234cb35f1ba2cca834b2dbe1302cf [email protected] github.com
github.com/ronf/asyncssh/releases/tag/v2.24.1 [email protected] github.com
github.com/ronf/asyncssh/security/advisories/GHSA-w29m-45fc-22v9 134c704f-9b21-4f2e-91b3-4a467353bcc0 github.com
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