Integer Overflow Vulnerability in libssh2: Potential Remote Code Execution Risk
Summary
DEBIAN-CVE-2019-3856: An integer overflow flaw, which could lead to an out of bounds write, was discovered in libssh2 before 1.8.1 in the way keyboard prompt requests 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 library that provides an API for implementing SSH2 client and server functionality. It is utilized in various applications to facilitate secure communication over networks. The library supports features such as secure file transfer and remote command execution. However, prior to version 1.8.1, libssh2 contained a critical vulnerability that could be exploited by attackers to execute arbitrary code on client systems.
Vulnerability Detail
An integer overflow flaw was discovered in libssh2 before version 1.8.1, specifically in the way keyboard prompt requests are parsed. This vulnerability allows a remote attacker, who compromises an SSH server, to potentially execute code on the client system when a user connects to the server. The flaw arises from improper handling of user input, leading to an out-of-bounds write, which can be exploited to gain unauthorized access or control over the affected system.
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
If updating the package is not immediately possible, consider restricting access to the affected SSH server or using alternative secure communication methods until the vulnerability can be addressed. Additionally, ensure that users are aware of the risks associated with connecting to potentially compromised servers.
Conclusion
The integer overflow vulnerability in libssh2 poses a significant risk of remote code execution on client systems. It is crucial for users and administrators to update to the patched version 1.8.0-2.1 or later to mitigate this risk. Awareness and proactive measures are essential to safeguard systems against potential exploitation.
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FAQ
The vulnerability is an integer overflow that can lead to out-of-bounds writes, allowing remote code execution on client systems.
You can use Vulert's playground at Vulert Scanner to check if your application is affected without needing to sign up.
Versions of libssh2 prior to 1.8.1 are vulnerable to this integer overflow issue.
Consider restricting access to the affected SSH server and inform users about the risks of connecting to potentially compromised servers.
You can visit Vulert at https://vulert.com for real-time monitoring and alerts on open-source vulnerabilities.
References
Related vulnerabilities
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