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Echo: python-asyncssh: security update to 2.20.0-1+e3

medium Tenable Self-Hosted Container Security Plugin ID 474827

Description

There are packages installed that are affected by a vulnerability referenced in the following CVE:

 - 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 2.24.0, _process_channel_open and
 _process_channel_open_confirmation in asyncssh/connection.py accept a peer-supplied send_pktsize value of
 zero. When channel data reaches SSHChannel._flush_send_buf in asyncssh/channel.py, the zero value causes
 each loop iteration to slice and remove zero bytes without reducing the send window, leaving the
 synchronous loop permanently true with no await point. A malicious SSH server can trigger the client path
 through SSH_MSG_CHANNEL_OPEN_CONFIRMATION before the first channel write, while an authenticated client
 can trigger the server path through SSH_MSG_CHANNEL_OPEN and freeze every current and future connection
 handled by the process. This vulnerability is fixed in 2.24.0. (CVE-2026-62949)

Solution

Update the python-asyncssh library and its related packages to version 2.20.0-1+e3 or later.

See Also

https://advisory.echohq.com/cve/CVE-2026-62949

Plugin Details

Severity: Medium

ID: 474827

Version: Revision 1.1

Type: Local

Published: 10/16/2026

Updated: 10/16/2026

Risk Information

VPR

Risk Factor: Low

Score: 3

Percentile: 23.6

CVSS v2

Risk Factor: Medium

Base Score: 6.8

Temporal Score: 5

Vector: CVSS2#AV:N/AC:L/Au:S/C:N/I:N/A:C

CVSS Score Source: CVE-2026-62949

CVSS v3

Risk Factor: Medium

Base Score: 6.5

Temporal Score: 5.7

Vector: CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

Vulnerability Information

Exploit Ease: No known exploits are available

Patch Publication Date: 9/19/2026

Vulnerability Publication Date: 9/16/2026

Reference Information

CVE: CVE-2026-62949