GPAC MP4Box CVE-2025-55663

Exploitation requires that an attacker supply a crafted MP4 file containing an unknown svcC box nested inside an av01 parent box, and that the target invoke MP4Box with the -add (track import) flag against that file, including the -ab (audio bitrate) option that triggers the bitrate-update code path leading to the vulnerable pointer dereference. The CVSS vector confirms no authentication or privileges are required (PR:N), but user interaction is required (UI:R) - the file must be actively processed by MP4Box rather than merely received. No special runtime configuration, network service, or elevated privilege is needed on the target host. Exploitation is limited by: (1) the requirement for user or process interaction with the malicious file; (2) impact confined to process crash with no code execution or data exfiltration vector identified; (3) scope unchanged, so a crash of MP4Box does not inherently compromise the host OS or adjacent processes unless MP4Box runs with elevated privileges in a pipeline.

The CVSS 3.1 vector (AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L) scores 4.3 MEDIUM, reflecting that exploitation requires no privileges and no special configuration but does require user interaction - specifically, a user or automated process must invoke MP4Box against the crafted file. Impact is confined to availability (process crash, DoS); there is no confidentiality or integrity exposure. No EPSS score was provided in the available data, so quantified exploitation probability cannot be stated. The vulnerability is not listed in CISA KEV, meaning active in-the-wild exploitation has not been formally confirmed. However, a public PoC MP4 file is available, which lowers the barrier for targeted use against media-processing pipelines that automatically ingest user-supplied content. In batch/automated transcoding environments where MP4Box is invoked without sandboxing on untrusted input, the effective user-interaction barrier is low, elevating real-world risk above the raw CVSS score implies. In interactive single-user deployments, risk is commensurate with the medium rating. The scope is unchanged and there is no privilege escalation vector identified.

An attacker crafts a malicious MP4 file containing an svcC box nested inside an av01 parent box - a public PoC file demonstrating exactly this is available at the reporter's GitHub - and delivers it to a target user or automated system that runs MP4Box with the -add import flag (e.g., MP4Box -add poc.mp4 -new /dev/null -ab 1024). The parser's unsupported-box handler leaves the sample entry pointer uninitialized, and Track_SetStreamDescriptor() dereferences it during bitrate update, causing an immediate SEGV crash of the MP4Box process, achieving denial of service against any pipeline dependent on that process.