Understanding CVE-2024-4741: A Deep Dive into OpenSSL's SSL_free_buffers Vulnerability

Hello LinuxPatch Customers,

We are here to discuss an important cybersecurity update that impacts certain versions of OpenSSL, a core software library for secure network communications. Today's focus is on a recently disclosed vulnerability identified as CVE-2024-4741. This issue has been classified with a severity rating of HIGH and possesses a score of 7.5.

Issue Summary:

The crux of this vulnerability lies in the improper handling of memory in the OpenSSL API function SSL_free_buffers. Under certain conditions, this function may attempt to access memory that has already been freed, leading to what's known as a "use after free" vulnerability. This particular type of memory misuse can lead to data corruption, crashes, and, worst-case scenario, the execution of arbitrary code.

Impact Summary:

This vulnerability specifically affects software that calls the SSL_free_buffers function directly. It’s worth noting that this function is not commonly used in applications, which somewhat mitigates the risk. However, for applications that do use this function, the implications can be severe. This function is generally used to free the internal buffer OpenSSL utilizes to process records received over a network. If this buffer is accessed after being freed, it can expose the system to potential exploits.

There are two primary scenarios where this vulnerability might be triggered:

  1. When the header of a network record is processed but the body of the record has not fully arrived. If SSL_free_buffers is called during this incomplete state, it could prematurely free the buffer still in use.
  2. When a complete record has been received, and parts of its data are being actively read by an application. Again, calling SSL_free_buffers could free the buffer while it's still in use.

Both scenarios outline how an error in handling the buffer’s lifecycle could lead to dangerous vulnerabilities, possibly even during normal application operation. Attackers could also engineer these scenarios to trigger the vulnerability deliberately.

To address and mitigate this issue, patches and updates are being prepared. As of now, we urge all users of OpenSSL, particularly those in versions prior to 3.0 and certain FIPS modules, to review and apply these updates as soon as they are made available to protect their systems against potential exploits.

For now, there are no known active exploits taking advantage of CVE-2024-4741, but the potential for damage is significant, and we recommend all our clients stay vigilant. Apply patches, monitor system logs, and ensure that your security practices are robust and up to date.

Stay safe and secure,

The LinuxPatch Team