CVE-2025-51602 is an out-of-bounds read vulnerability classified under CWE-125 found in the mmstu.c module of the VideoLAN VLC media player versions prior to 3.0.22. The flaw is triggered when VLC processes a crafted 0x01 response from an MMS (Microsoft Media Server) streaming server. This malformed response causes VLC to read memory outside the intended buffer boundaries, leading to undefined behavior that can cause the application to crash, resulting in a denial of service (DoS). The vulnerability does not allow for code execution or data leakage, but it compromises the availability of the VLC media player. The attack vector is network-based (AV:N), meaning an attacker can exploit this remotely without requiring privileges (PR:N) or user interaction (UI:N). However, the attack complexity is high (AC:H), indicating that exploitation requires specific conditions or knowledge about the MMS server response format. The vulnerability affects all VLC versions before 3.0.22, which is a widely used open-source media player globally. No public exploits or active exploitation campaigns have been reported to date. The absence of patch links suggests that a fix may be forthcoming or that users should upgrade to the latest VLC version once it includes the patch. The vulnerability was reserved in mid-2025 and published in early 2026, indicating a recent discovery and disclosure.

For European organizations, the primary impact of CVE-2025-51602 is potential denial of service affecting systems that rely on VLC media player for media playback, streaming, or broadcasting. This could disrupt media workflows, internal communications, or customer-facing services that utilize MMS streaming. Although the vulnerability does not compromise data confidentiality or integrity, repeated crashes or service interruptions could degrade user experience and operational continuity. Organizations in sectors such as media production, broadcasting, education, and public services that use VLC extensively are at higher risk. The medium severity and high attack complexity reduce the likelihood of widespread exploitation, but targeted attacks against critical media infrastructure remain a concern. Additionally, the lack of known exploits in the wild provides a window for proactive mitigation before active attacks emerge.

1. Upgrade VLC media player to version 3.0.22 or later as soon as the patch addressing CVE-2025-51602 is officially released. 2. Until patched, restrict or monitor network traffic to and from MMS streaming servers, especially those that are untrusted or external, to reduce exposure to crafted malicious responses. 3. Employ network-level intrusion detection or prevention systems (IDS/IPS) that can identify anomalous MMS traffic patterns indicative of exploitation attempts. 4. For organizations deploying VLC in automated or embedded environments, implement application whitelisting and sandboxing to limit the impact of potential crashes. 5. Educate IT and security teams about this vulnerability to ensure timely response to any related incidents. 6. Regularly review and update media player software and dependencies as part of patch management policies to minimize exposure to similar vulnerabilities.