CVE-2025-63095 is a vulnerability identified in the BitstreamWriter::write_bits() function of the Tempus Ex hello-video-codec version 0.1.0. The root cause is improper input validation (CWE-20), where the function fails to correctly verify or sanitize input bitstreams before processing. This flaw can be exploited by an attacker who crafts malicious input data that, when processed by the vulnerable function, causes the application to crash or enter an unstable state, resulting in a Denial of Service (DoS). The attack vector is remote network access (AV:N), requiring no privileges (PR:N) but does require user interaction (UI:R), such as opening or processing a malicious video stream or file. The vulnerability affects availability (A:H) but does not impact confidentiality or integrity. The CVSS v3.1 base score is 6.5, reflecting medium severity. No patches or fixes have been released yet, and no known exploits are reported in the wild. The vulnerability is particularly relevant for applications or services that utilize the hello-video-codec for video encoding or decoding, potentially including streaming platforms, video conferencing tools, or multimedia processing software. The lack of input validation suggests that attackers could craft bitstreams that trigger buffer overflows, infinite loops, or resource exhaustion within the write_bits() function, leading to crashes or degraded service performance.

For European organizations, the primary impact of CVE-2025-63095 is service disruption due to Denial of Service conditions in applications using the hello-video-codec. This could affect multimedia services such as video streaming platforms, conferencing tools, or any software relying on this codec for video processing. Disruptions could lead to loss of availability, impacting business continuity, customer experience, and potentially causing financial losses. Although confidentiality and integrity are not directly compromised, repeated or targeted DoS attacks could degrade trust in services or force costly incident responses. Organizations in sectors heavily dependent on real-time video communication or streaming, such as media companies, telecommunications, and remote work providers, may face operational challenges. Additionally, the absence of patches increases exposure duration. The medium severity suggests a moderate risk, but the ease of remote exploitation and lack of required privileges elevate the threat profile for affected deployments.

To mitigate CVE-2025-63095, organizations should first identify all systems and applications utilizing the Tempus Ex hello-video-codec v0.1.0. Until official patches are available, implement strict input validation and sanitization at the application layer to detect and reject malformed or suspicious video bitstreams before they reach the vulnerable function. Employ rate limiting and resource usage monitoring on services handling video streams to detect and mitigate potential DoS attempts. Consider deploying application-layer firewalls or intrusion prevention systems with custom rules to block known malicious payload patterns targeting the codec. Engage with software vendors or development teams to prioritize patch development and testing. For critical systems, isolate or sandbox video processing components to contain potential crashes and prevent cascading failures. Maintain up-to-date backups and incident response plans to quickly recover from service disruptions. Finally, monitor threat intelligence sources for updates on exploits or patches related to this vulnerability.