Critical Authentication Bypass in AsyncSSH Package
Summary
CVE-2018-7749: The SSH server implementation of AsyncSSH before 1.12.1 does not properly check whether authentication is completed before processing other requests. Affects python-asyncssh across 2 version ranges.
< 1.12.1-1
< c161e26cdc0d41b745b63d9f17b437f073bf7ba4
Fixed in 1.12.1-1. How to fix ↓
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Background
AsyncSSH is a Python package that provides an asynchronous SSH client and server implementation. It is designed for high-performance applications that require SSH capabilities, allowing for secure remote connections and file transfers. The package is widely used in various applications due to its non-blocking architecture, which enhances performance in networked environments. However, a significant vulnerability has been identified that compromises its authentication process.
Vulnerability Detail
The vulnerability, identified as CVE-2018-7749, affects the SSH server implementation of AsyncSSH versions prior to 1.12.1. The flaw arises from improper checks on whether authentication has been completed before processing other requests. This oversight allows a malicious actor using a customized SSH client to bypass the authentication step entirely, potentially leading to unauthorized access and control over the server. The severity of this vulnerability is underscored by its CVSS score of 9.8, indicating a critical risk to affected systems.
How To Fix
Minimum fixed version
1.12.1-1
This is the first release that contains the fix.
sudo apt-get install --only-upgrade python-asyncsshTip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
As a temporary workaround, users can restrict access to the SSH server by implementing firewall rules or using SSH configuration settings to limit connections to trusted IP addresses until the package is updated.
Conclusion
The CVE-2018-7749 vulnerability in the AsyncSSH package poses a significant risk due to its potential for unauthorized access. Users are strongly advised to upgrade to version 1.12.1 or later to mitigate this risk. Additionally, temporary workarounds can be employed to enhance security until the update is applied.
See every vulnerability recorded for python-asyncssh →
FAQ
CVE-2018-7749 is a vulnerability in the AsyncSSH package that allows unauthorized access by bypassing the authentication process.
You can use the Vulert playground at Vulert Scanner to check if your application is affected by this vulnerability without requiring any signup.
If exploited, this vulnerability can lead to unauthorized access to the SSH server, allowing attackers to execute commands, access sensitive data, or disrupt services.
Yes, you can implement firewall rules to restrict access to the SSH server and limit connections to trusted IP addresses as a temporary measure.
The CVSS score of CVE-2018-7749 is 9.8, indicating a critical level of risk associated with this vulnerability.
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