CVE-2019-16747 in MatrixSSL
Summary
by MITRE • 12/31/2020
In MatrixSSL before 4.2.2 Open, the DTLS server can encounter an invalid pointer free (leading to memory corruption and a daemon crash) via a crafted incoming network message, a different vulnerability than CVE-2019-14431.
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Analysis
by VulDB Data Team • 06/16/2026
The vulnerability in MatrixSSL versions prior to 4.2.2 Open represents a critical memory safety issue that affects the DTLS server implementation within the cryptographic library. This flaw manifests as an invalid pointer free operation that occurs when processing crafted network messages, leading to potential memory corruption and subsequent daemon crashes. The vulnerability specifically impacts the DTLS server functionality and operates at the network protocol level where malformed packets can trigger unexpected behavior in the memory management subsystem.
The technical root cause of this vulnerability stems from improper handling of memory pointers during DTLS server processing of incoming network traffic. When the server receives a specially crafted message, the memory management functions attempt to free a pointer that either has already been freed or was never properly allocated, resulting in undefined behavior. This type of vulnerability falls under the category of memory corruption issues that are commonly classified as CWE-415 Double Free or CWE-416 Use After Free, though the specific manifestation here involves invalid pointer dereference during cleanup operations. The flaw demonstrates a classic memory safety issue where the server fails to validate pointer states before attempting memory deallocation operations.
The operational impact of this vulnerability extends beyond simple service disruption to potentially enable more sophisticated attack vectors. An attacker who can successfully send a crafted DTLS message can force the daemon to crash, leading to denial of service conditions that can affect legitimate users and potentially provide cover for more complex attacks. The vulnerability is particularly concerning because it operates at the protocol level where network traffic is processed, making it accessible through standard network communication channels. This vulnerability represents a significant risk to systems relying on MatrixSSL for secure communications, as it can be exploited without requiring authentication or elevated privileges, and the impact can be immediate and severe.
Mitigation strategies for this vulnerability require immediate patching of affected MatrixSSL implementations to version 4.2.2 or later where the memory management issues have been addressed. Organizations should also implement network monitoring to detect unusual traffic patterns that might indicate exploitation attempts, and consider implementing intrusion detection systems that can identify malformed DTLS packets. The fix typically involves proper validation of pointer states before memory deallocation operations and ensuring that memory management functions properly handle edge cases in packet processing. Security teams should also conduct thorough testing of patched systems to ensure that the fix does not introduce regressions in functionality while maintaining the security improvements. This vulnerability aligns with ATT&CK technique T1499.004 for network denial of service and demonstrates the importance of proper memory management in cryptographic libraries.