The vulnerability is a heap buffer overflow located in vaapi_hevc_start_frame() in libavcodec/vaapi_hevc.c of FFmpeg. It occurs when the decoder copies unbounded picture parameter set (PPS) tile counts into fixed‑size arrays, allowing an attacker to supply a crafted HEVC bitstream with many tiles. Overwrite beyond the allocated heap region results in corrupted memory within the application that uses VAAPI for decoding. This corruption can lead to crashes, data tampering, or, in the worst case, execution of attacker‑controlled code, compromising confidentiality, integrity, and availability of the host.

FFmpeg, all releases through 9.0.2, including both the open‑source binary and the libavcodec components that perform VAAPI‑based HEVC decoding.

The CVSS score of 7.3 indicates a high severity risk. No EPSS score is available, so the current exploitation probability is uncertain, and the vulnerability is not listed in the CISA KEV catalog. Attackers can exploit the flaw by presenting a malicious media stream to a vulnerable application that performs HEVC decoding via VAAPI, typically through local or remote channels that supply the bitstream. The absence of checks on tile counts means the exploitation can succeed without privileged access, though successful exploitation may lead to remote code execution or denial of service depending on how the memory corruption is used.