Integer Overflow Vulnerability in libssh2: Potential for Out-of-Bounds Read
Summary
DEBIAN-CVE-2019-13115: In libssh2 before 1.9.0, kex_method_diffie_hellman_group_exchange_sha256_key_exchange in kex.c has an integer overflow that could lead to an out-of-bounds read in the way packets are read from the server. Affects libssh2 versions < 1.9.0-1. Fixed in 1.9.0-1. 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
Habilume
Habit tracker with a companion that grows with you
Complete habits, earn Lume Points, and watch your Lume grow as you stay consistent.
Background
libssh2 is a widely used library that provides an API for implementing SSH2 client functionality. It is utilized in various applications for secure communication over networks. The library supports multiple key exchange methods and is designed to facilitate secure file transfers and remote command execution. However, prior to version 1.9.0, libssh2 was found to have a critical vulnerability that could compromise the security of applications relying on it.
Vulnerability Detail
In libssh2 before version 1.9.0, the function kex_method_diffie_hellman_group_exchange_sha256_key_exchange in kex.c contains an integer overflow vulnerability. This flaw can lead to an out-of-bounds read when packets are processed from a compromised SSH server. A remote attacker could exploit this vulnerability to disclose sensitive information or trigger a denial of service condition on the client system when a user connects to the affected server. This issue is linked to a mistake in the _libssh2_check_length function and is distinct from other vulnerabilities addressed in version 1.8.1, such as CVE-2019-3855.
How To Fix
Minimum fixed version
1.9.0-1
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 workaround, users can avoid connecting to untrusted SSH servers until the package is updated. Additionally, implementing strict server verification and using alternative secure communication methods may help mitigate risks.
Conclusion
The integer overflow vulnerability in libssh2 poses significant risks to applications utilizing this library for secure communications. It is crucial for users to update to the patched version 1.9.0-1 or later to mitigate potential threats. Employing best practices for server verification can also enhance security until updates are applied.
See every vulnerability recorded for libssh2 →
FAQ
libssh2 is a library that provides an API for SSH2 client functionality, enabling secure communication over networks.
The vulnerability involves an integer overflow that can lead to out-of-bounds reads, potentially allowing attackers to access sensitive information or cause denial of service.
You can use the Vulert playground at Vulert Scanner to check if your application is affected by this vulnerability without any signup.
If immediate updates are not possible, avoid connecting to untrusted SSH servers and consider implementing strict server verification.
Vulert provides real-time monitoring and alerts for open-source vulnerabilities using just a manifest file like package-lock.json. Visit https://vulert.com for more details.
References
Related vulnerabilities
Recent vulnerabilities recorded for libssh2.
Habilume
Habit tracker with a companion that grows with you
Complete habits, earn Lume Points, and watch your Lume grow as you stay consistent.
