Integer Overflow Vulnerability in libssh2: Potential Remote Code Execution Risk
Summary
DEBIAN-CVE-2019-3855: An integer overflow flaw which could lead to an out of bounds write was discovered in libssh2 before 1.8.1 in the way packets are read from the server. 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 implementation of the SSH2 protocol, allowing secure communication over unsecured networks. It is utilized in various applications for secure file transfers and remote command execution. The library is essential for developers needing to integrate SSH capabilities into their software. However, a critical vulnerability has been identified that could compromise the security of systems using this library.
Vulnerability Detail
An integer overflow flaw was discovered in libssh2 versions prior to 1.8.1, specifically in the way packets are read from the server. This vulnerability allows a remote attacker to exploit the flaw by sending specially crafted packets, potentially leading to an out-of-bounds write. If successfully exploited, this could allow the attacker to execute arbitrary code on the client system when a user connects to the compromised SSH server.
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 measure, users can avoid connecting to untrusted SSH servers until the package is updated. Additionally, implementing strict firewall rules to limit access to SSH services can help mitigate the risk.
Conclusion
The integer overflow vulnerability in libssh2 poses a significant risk, allowing remote code execution through crafted packets. It is crucial for users to update to the patched version to safeguard their systems. Implementing workarounds can provide temporary relief while awaiting updates.
See every vulnerability recorded for libssh2 →
FAQ
libssh2 is a library that implements the SSH2 protocol, enabling secure communication for file transfers and remote command execution.
The integer overflow vulnerability allows remote attackers to send crafted packets that can lead to out-of-bounds writes, potentially enabling code execution on the client system.
You can use Vulert's playground at Vulert Scanner to check if your application is affected by this vulnerability without requiring any signup.
If an immediate update is not possible, avoid connecting to untrusted SSH servers and consider implementing firewall rules to restrict SSH access.
You can visit Vulert at https://vulert.com, which monitors and alerts for open-source vulnerabilities in your software using just a manifest file.
References
Related vulnerabilities
Recent vulnerabilities recorded for libssh2.
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