Critical Out of Bounds Read Vulnerability in libssh2 Package
Summary
DEBIAN-CVE-2019-3861: An out of bounds read flaw was discovered in libssh2 before 1.8.1 in the way SSH packets with a padding length value greater than the packet length are parsed. Affects libssh2 versions < 1.8.0-2.1. Fixed in 1.8.0-2.1. How to fix ↓
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Background
libssh2 is a widely used C library that provides an API for implementing SSH2 client and server functionality. It allows applications to securely connect to remote servers, transfer files, and execute commands. The library is essential for secure communications in various applications, making it crucial for developers to ensure its integrity and security. However, a vulnerability has been identified that could compromise its security.
Vulnerability Detail
An out of bounds read flaw was discovered in libssh2 versions prior to 1.8.1. This vulnerability arises from the improper parsing of SSH packets that have a padding length value greater than the actual packet length. A remote attacker who successfully compromises an SSH server could exploit this flaw to cause a Denial of Service (DoS) or potentially read sensitive data from the client’s memory, leading to severe security implications.
How To Fix
Minimum fixed version
1.8.0-2.1
This is the first release that contains the fix.
sudo apt-get install --only-upgrade libssh2Tip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
As a temporary workaround, users can limit access to the SSH server or implement firewall rules to restrict incoming connections until the package is updated. However, this is not a permanent solution and should be followed by an update as soon as possible.
Conclusion
The out of bounds read vulnerability in the libssh2 package poses significant risks to applications relying on this library for secure communications. It is crucial for users to update to the patched version to mitigate these risks. Utilizing tools like Vulert can help monitor and alert for such vulnerabilities in real-time.
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FAQ
The vulnerability is an out of bounds read flaw that can lead to Denial of Service or unauthorized data access.
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If exploited, this vulnerability can lead to service interruptions or unauthorized access to sensitive information in memory.
Yes, the patched version of libssh2 is 1.8.0-2.1 or later, which addresses this vulnerability.
Implement firewall rules to restrict access to the SSH server as a temporary measure until the package can be updated.
References
Related vulnerabilities
Recent vulnerabilities recorded for libssh2.
