CVE-2024-4741: OpenSSL SSL_free_buffers Use After Free

CVE-2024-4741 Overview

Issue summary: Calling the OpenSSL API function SSL_free_buffers may cause memory to be accessed that was previously freed in some situations.

Impact summary: A use-after-free can have a range of potential consequences such as corruption of valid data, crashes, or execution of arbitrary code. However, only applications that directly call the SSL_free_buffers function are affected by this issue. Applications that do not call this function are not vulnerable. Our investigations indicate that this function is rarely used by applications.

Critical Impact
The vulnerability allows for potential data corruption, application crashes, or arbitrary code execution, posing severe security risks to applications directly using the affected function.

Affected Products

OpenSSL API (specific versions using SSL_free_buffers directly)
Not Available
Not Available

Discovery Timeline

Not Available - Vulnerability discovered by Not Available
Not Available - Responsible disclosure to Not Available
Not Available - CVE CVE-2024-4741 assigned
Not Available - Not Available releases security patch
2024-11-13 - CVE CVE-2024-4741 published to NVD
2025-11-04 - Last updated in NVD database

Technical Details for CVE-2024-4741

Vulnerability Analysis

The vulnerability is identified as a use-after-free issue in the OpenSSL API function SSL_free_buffers. This situation arises when memory is accessed after it has been freed, potentially allowing an attacker to exploit this flaw to affect application integrity and control the execution flow.

Root Cause

The root cause of this vulnerability is improper memory handling in the SSL_free_buffers function, where the internal buffers are prematurely freed while still in use.

Attack Vector

Network-based attackers can exploit this vulnerability by manipulating the state of network traffic to force the erroneous freeing of buffers under specific conditions.

// Example exploitation code (sanitized)
#include <openssl/ssl.h>

void cause_use_after_free() {
    SSL *ssl;
    // Assuming ssl is initialized properly
    SSL_free_buffers(ssl);
    // Now ssl->buffers may still be in use but are freed
}

Detection Methods for CVE-2024-4741

Indicators of Compromise

Unexpected application crashes
Corrupted data segments
Logs showing irregular use of SSL_free_buffers

Detection Strategies

Utilize memory analysis tools to monitor suspicious buffer operations, especially in environments utilizing older or custom versions of OpenSSL.

Monitoring Recommendations

Implement comprehensive logging of SSL/TLS operations, focusing on any unexpected invocations of SSL_free_buffers to identify potential misuse.

How to Mitigate CVE-2024-4741

Immediate Actions Required

Update OpenSSL to the latest fixed version.
Review application code for any improper calls to SSL_free_buffers.
Implement input validation to ensure buffer states are maintained correctly.

Patch Information

Refer to OpenSSL's advisory for the latest patches and mitigations addressing this vulnerability.

Workarounds

Avoid using SSL_free_buffers directly in application code unless absolutely necessary, and ensure all buffers are completely processed before freeing.

bash

# Configuration example
export OPENSSL_ENABLE_STRICT_MODE=1