# CVE-2026-54591: AsyncSSH path traversal in SCP client

Source: https://junglewise.ai/threats/cve-2026-54591-asyncssh-path-traversal-in-scp-client  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-08. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-54591 · Severity: high · CVSS 8.1 · Published 2026-07-08

AsyncSSH is a Python SSH library widely used for secure remote file transfer via SCP. A malicious SSH server can exploit the SCP client to write arbitrary files anywhere on the user's filesystem by sending specially crafted directory traversal sequences (e.g., `../`). This can lead to remote code execution by overwriting shell configuration files like `~/.bashrc` or SSH authorization files, allowing attackers to execute code when the user next logs in or opens a terminal.

Technologies: [asyncssh (PyPI)](https://junglewise.ai/threats/technologies/pypi-asyncssh). Vendors: [PyPI](https://junglewise.ai/threats/vendors/pypi).

## Quick answers

**Is CVE-2026-54591 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-54591 being exploited in the wild.

**How severe is CVE-2026-54591?** High severity, with a CVSS score of 8.1, published 8 July 2026.

**Which products and versions are affected?** asyncssh (PyPI) ECOSYSTEM:introduced=0,fixed=2.23.1.

**Is there a fix for CVE-2026-54591?** Yes. asyncssh (PyPI): upgrade to 2.23.1 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-54591 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-54591?** Check whether you run asyncssh (PyPI) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- asyncssh (PyPI): upgrade to 2.23.1 or later

  ```sh
  pip install "asyncssh>=2.23.1"
  ```


## Technical details

This is a path traversal (CWE-22) vulnerability in AsyncSSH's SCP receive implementation. The vulnerability exists in the `_parse_cd_args()` function (scp.py:134-142) and `_recv_files()` function (scp.py:706-713), which fail to sanitize server-supplied filenames before joining them with the target directory path using `posixpath.join()`. An attacker controlling a malicious SSH server can send SCP protocol messages with filenames containing `../` sequences to escape the intended download directory. By chaining directory traversal commands via the SCP `D` (directory) action, an attacker can overwrite critical files such as `~/.bashrc`, `~/.profile`, `~/.ssh/rc`, or `~/.ssh/authorized_keys`. The vulnerability requires user interaction (the application must call `asyncssh.scp()` to download from an attacker-controlled server) and network connectivity, but no authentication or special privileges. Remote code execution is achievable when the user's next login/terminal session sources the modified files. This is the same vulnerability class as CVE-2019-6111 in OpenSSH. A patch is available in AsyncSSH version 2.23.1 and later.

## Affected products

- ronf asyncssh <= 2.23.0

## Identifiers

- CVE-2026-54591
- GHSA-2wxc-x7rj-hg8f
- PYSEC-2026-3808

## Timeline

- 2026-06-16: disclosed
- 2026-06-16: patched: AsyncSSH 2.23.1 released
- 2026-08-26: advisory

## References

- [https://api.github.com/users/Jaden-Furtado](https://api.github.com/users/Jaden-Furtado)
- [https://github.com/Jaden-Furtado](https://github.com/Jaden-Furtado)
- [https://api.github.com/users/Jaden-Furtado/gists%7B/gist_id%7D](https://api.github.com/users/Jaden-Furtado/gists%7B/gist_id%7D)
- [https://api.github.com/users/Jaden-Furtado/repos](https://api.github.com/users/Jaden-Furtado/repos)
- [https://avatars.githubusercontent.com/u/136704191?v=4](https://avatars.githubusercontent.com/u/136704191?v=4)
- [https://api.github.com/users/Jaden-Furtado/events%7B/privacy%7D](https://api.github.com/users/Jaden-Furtado/events%7B/privacy%7D)

## Related threats

- [AsyncSSH event-loop infinite loop via zero maximum packet size](https://junglewise.ai/threats/cve-2026-62949-asyncssh-event-loop-infinite-loop-via-zero-maximum-packet-size)
- [ronf AsyncSSH path traversal in AuthorizedKeysFile](https://junglewise.ai/threats/cve-2026-45309-ronf-asyncssh-path-traversal-in-authorizedkeysfile)
- [ronf AsyncSSH path traversal in AuthorizedKeysFile username substitution](https://junglewise.ai/threats/cve-2026-54590-ronf-asyncssh-path-traversal-in-authorizedkeysfile-username)
- [AsyncSSH vulnerable to Prefix Truncation Attack (a.k.a. Terrapin Attack) against ChaCha20-Poly1305 and Encrypt-then-MAC](https://junglewise.ai/threats/asyncssh-vulnerable-to-prefix-truncation-attack-a-k-a-terrapin-attack-70e933b5)
- [AsyncSSH Rogue Session Attack](https://junglewise.ai/threats/cve-2023-46446-asyncssh-rogue-session-attack)