Integer Overflow Vulnerability in libssh2: Potential Remote Code Execution Risk
Summary
UBUNTU-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 < 1.4.3-2ubuntu0.2+esm2. Fixed in 1.4.3-2ubuntu0.2+esm2. How to fix ↓
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Background
libssh2 is a widely used library that provides an API for implementing SSH2 client functionality. It is utilized in various applications to enable secure communication over networks. The library is designed to handle SSH connections, including authentication and data transfer. However, a critical vulnerability has been identified that affects versions prior to 1.8.1, which could allow attackers to exploit the library's handling of keyboard prompt requests.
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 could lead to an out-of-bounds write, allowing a remote attacker who compromises an SSH server to execute arbitrary code on the client system when a user connects to the server. The CVSS score for this vulnerability is 7.5, indicating a high severity level.
How To Fix
Minimum fixed version
1.4.3-2ubuntu0.2+esm2
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 avoid connecting to untrusted SSH servers until the package is updated. Additionally, consider using alternative libraries or methods for SSH connections that do not rely on libssh2 until the vulnerability is resolved.
Conclusion
The integer overflow vulnerability in libssh2 poses a significant risk, allowing remote code execution through compromised SSH servers. It is crucial for users to update their libssh2 packages to the latest patched versions to mitigate this risk. Utilizing tools like Vulert can help monitor and identify vulnerabilities in your applications effectively.
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FAQ
libssh2 is a library that provides an API for SSH2 client functionality, enabling secure communication over networks.
The vulnerability allows an attacker to execute arbitrary code on the client system by exploiting the way keyboard prompt requests are handled.
You can use Vulert, which monitors and alerts for open-source vulnerabilities in your software. Visit Vulert Scanner to check your application without any signup.
The CVSS score of this vulnerability is 7.5, indicating a high severity level.
If you cannot update the package, avoid connecting to untrusted SSH servers and consider using alternative libraries for SSH connections.
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