Out of Bounds Read Vulnerability in libssh2 - Denial of Service Risk
Summary
DEBIAN-CVE-2019-3859: An out of bounds read flaw was discovered in libssh2 before 1.8.1 in the _libssh2_packet_require and _libssh2_packet_requirev functions. Affects libssh2 versions < 1.8.0-2.1. Fixed in 1.8.0-2.1. How to fix ↓
Check if this vulnerability affects your application
Upload a manifest or SBOM and we'll show whether you're affected, plus every other risky package in the same scan.
No signup required · Results in about 60 seconds
Background
libssh2 is a widely used library that implements the SSH2 protocol, enabling secure communication over unsecured networks. It is utilized in various applications for secure file transfers and remote command execution. The library's functionality is critical for maintaining data integrity and confidentiality in client-server communications. However, vulnerabilities in libssh2 can expose applications to significant security risks, including unauthorized access and denial of service attacks.
Vulnerability Detail
An out of bounds read flaw was discovered in libssh2 before version 1.8.1, specifically in the _libssh2_packet_require and _libssh2_packet_requirev functions. This vulnerability allows a remote attacker who compromises an SSH server to potentially cause a Denial of Service or read sensitive data from the client memory. The flaw arises from improper handling of packet data, which can lead to memory access violations.
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 restrict access to the SSH server or implement network-level security controls to limit exposure to potential attacks while awaiting the patch. Additionally, monitoring for unusual activity on the SSH server can help mitigate risks.
Conclusion
The out of bounds read vulnerability in libssh2 poses significant risks, including Denial of Service and potential data exposure. It is crucial for users to update to the latest version to safeguard their applications. Utilizing tools like Vulert can help monitor and alert for such vulnerabilities in real-time, ensuring better security practices.
See every vulnerability recorded for libssh2 →
FAQ
The vulnerability can lead to Denial of Service attacks and unauthorized access to sensitive data in client memory.
You can use Vulert's playground at Vulert Scanner to check if your application is affected by this vulnerability without any signup.
All versions of libssh2 prior to 1.8.1 are affected by this vulnerability.
Yes, updating to version 1.8.0-2.1 or later will permanently fix the vulnerability.
If immediate updates are not possible, consider implementing network security measures and monitoring to reduce the risk of exploitation.
References
Related vulnerabilities
Recent vulnerabilities recorded for libssh2.
