Integer Overflow Vulnerability in libssh2: Potential Remote Code Execution Risk
Summary
DEBIAN-CVE-2019-3857: An integer overflow flaw which could lead to an out of bounds write was discovered in libssh2 before 1.8.1 in the way SSH_MSG_CHANNEL_REQUEST packets with an exit signal 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 communications over a network. The library supports features such as authentication, encryption, and data integrity. However, prior to version 1.8.1, libssh2 was found to have a critical vulnerability that could be exploited by remote attackers, leading to severe security risks.
Vulnerability Detail
An integer overflow flaw was discovered in libssh2 before version 1.8.1, specifically in the parsing of SSH_MSG_CHANNEL_REQUEST packets that contain an exit signal. This flaw allows a remote attacker to potentially execute arbitrary code on the client system when a user connects to a compromised SSH server. The vulnerability arises from improper handling of input data, which can lead to out-of-bounds writes, compromising the integrity and security of 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 immediate updating is not feasible, consider restricting access to the SSH server or implementing firewall rules to limit exposure. Additionally, avoid connecting to untrusted SSH servers until the vulnerability is resolved.
Conclusion
The integer overflow vulnerability in libssh2 poses a significant risk to users, allowing potential remote code execution. It is crucial to update to the latest version to safeguard against exploitation. Users are encouraged to monitor their systems and utilize tools like Vulert for real-time vulnerability alerts.
See every vulnerability recorded for libssh2 →
FAQ
The vulnerability is an integer overflow that can lead to out-of-bounds writes, potentially allowing remote code execution.
You can use Vulert's playground at Vulert Scanner to check if your application is affected by this vulnerability without needing to sign up.
If exploited, attackers could execute arbitrary code on the client system, leading to data breaches or system compromise.
Yes, the vulnerability is fixed in libssh2 version 1.8.0-2.1 and later.
Consider implementing firewall rules to restrict access to your SSH server and avoid connecting to untrusted servers.
References
Related vulnerabilities
Recent vulnerabilities recorded for libssh2.
