Critical Memory Management Flaw in libssh: Potential Heap Corruption Risk
Summary
UBUNTU-CVE-2025-5351: A flaw was found in the key export functionality of libssh. Affects libssh versions < 0.10.6-2ubuntu0.1. Fixed in 0.10.6-2ubuntu0.1. How to fix ↓
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Background
libssh is a widely used library that provides an implementation of the SSH (Secure Shell) protocol, allowing secure communication over unsecured networks. It is utilized in various applications for secure data transmission, remote command execution, and secure file transfers. The library's functionality is critical for maintaining the integrity and confidentiality of data in transit. However, a recently discovered vulnerability poses a significant risk to applications relying on libssh, particularly in low-memory scenarios.
Vulnerability Detail
A flaw was found in the key export functionality of libssh, specifically in the internal function responsible for converting cryptographic keys into serialized formats. During error handling, a memory structure is freed but not cleared, leading to a potential double free issue if an additional failure occurs later in the function. This condition may result in heap corruption or application instability, posing a risk to system reliability where key export operations are performed. The CVSS score for this vulnerability is 4.2, indicating a medium severity level.
How To Fix
Minimum fixed version
0.10.6-2ubuntu0.1
This is the first release that contains the fix.
sudo apt-get install --only-upgrade libsshTip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
As a temporary measure, consider limiting the use of key export operations in low-memory environments until the package can be updated. Additionally, monitor application logs for any unusual behavior that may indicate instability due to this vulnerability.
Conclusion
The vulnerability in libssh presents a significant risk due to improper memory management during key export operations. It is crucial for users to update to the patched versions of the library to mitigate potential heap corruption and application instability. Utilizing tools like Vulert can help monitor for such vulnerabilities effectively.
See every vulnerability recorded for libssh →
FAQ
The vulnerability involves a flaw in the key export functionality that can lead to heap corruption due to improper memory management during error handling.
You can use Vulert, which monitors and alerts for open-source vulnerabilities in your software. Check your application against the manifest file using the Vulert playground at Vulert Scanner.
The consequences may include application instability, heap corruption, and potential security risks in systems where key export operations are performed.
Yes, patches are available for both Ubuntu 24.04 LTS and Ubuntu 25.04. Updating to the specified versions will resolve the issue.
If immediate updates are not possible, limit the use of key export operations and monitor your application for any signs of instability.
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