Welcome to our detailed exploration of CVE-2024-5535, a critical security vulnerability identified within OpenSSL. This issue, despite being critical in terms of potential impact, primarily affects very specific scenarios involving configuration or programming errors in the way applications utilize OpenSSL for secure communications.
Severity and Score: The vulnerability has been rated critical with a severity score of 9.1, implying a significant potential risk under certain conditions.
Issue Summary: The core issue arises when the OpenSSL API function SSL_select_next_proto is invoked with an empty supported client protocols buffer. Normally used for Application Layer Protocol Negotiation (ALPN) or the now deprecated Next Protocol Negotiation (NPN), this function performs protocol selection based on client and server preferences. Incorrect invocation of this function—specifically with a zero-length client list—can result in a buffer overread. This could, under rare circumstances, allow up to 255 bytes of arbitrary private data from memory to be inadvertently sent to the peer, leading to potential data leakage and confidentiality breaches.
Software Impact: Due to its integration in server and client-side applications that use TLS (Transport Layer Security), particularly those employing ALPN or the less commonly used NPN, OpenSSL’s functionality is crucial for ensuring secure data transmissions over networks. The impacted OpenSSL versions include FIPS module versions 3.3, 3.2, 3.1, and 3.0.
Impact on Your Systems: Fortunately, unless your applications are misconfigured or a programming mistake has led to improper use of the affected API, the risk of this vulnerability affecting your systems is low. It primarily concerns setups still utilizing the outdated NPN or those that may not handle ALPN handshakes correctly.
Patch Information: As of now, OpenSSL has not released new versions due to the low severity and specific circumstances required for exploitation. However, updates will include fixes in upcoming releases.
We encourage all LinuxPatch users to review their systems and configurations, especially if they directly interact with OpenSSL functionalities. Verify that appropriate lists of protocols are passed to SSL_select_next_proto and that possible errors in the handshake phase are adequately handled.
Stay vigilant and proactive by regularly updating your systems. For comprehensive patch management and updates for Linux servers, visit LinuxPatch.com.
By staying informed and prepared, you can safeguard your systems against potential security threats like CVE-2024-5535 and maintain robust security protocols.