CVE-2025-55648: GPAC MP4Box Heap Buffer Overflow DoS Vulnerability

Technical summary

The vulnerability exists in the gf_opus_parse_packet_header function within media_tools/av_parsers.c, where a heap buffer overflow can occur during the parsing of Opus audio packet headers in MP4 containers. The flaw stems from insufficient bounds checking when processing crafted packet header data, allowing an attacker to write beyond allocated heap memory. This memory corruption triggers a denial of service condition, typically resulting in application crash or undefined behavior. The CVSS 3.1 vector (CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H) reflects local attack surface, low complexity, user interaction requirement, and high availability impact with no confidentiality or integrity compromise.

Business impact

Organizations using MP4Box—whether for media transcoding pipelines, video analysis, quality assurance workflows, or broadcast preparation—face operational disruption if users encounter malicious MP4 files. While the vulnerability does not leak data or corrupt files, repeated crashes degrade productivity and may interrupt time-sensitive media processing tasks. In supply-chain scenarios where media files are exchanged with external partners or pulled from untrusted sources, this becomes a vector for workflow sabotage or denial of service attacks against downstream systems.

Affected systems

GPAC MP4Box v2.4 is directly affected. Organizations should verify whether other versions in the 2.x line or earlier releases exhibit the same flaw by consulting the GPAC project's advisories and commit history. Any environment where MP4Box is deployed—including CI/CD pipelines, video editing suites, media servers, and development workstations—poses a potential exposure if users process untrusted MP4 files.

Exploitability

Exploitation is straightforward: an attacker crafts a malicious MP4 file with a malformed Opus packet header and delivers it to a user who opens it with MP4Box. No authentication, elevated privileges, or network access is required. The user interaction barrier is low because opening media files is a routine operation. However, weaponization requires knowledge of the specific packet structure to trigger the buffer overflow, so mass automated exploitation is unlikely without public proof-of-concept code. The vulnerability is not currently tracked in the CISA Known Exploited Vulnerabilities (KEV) catalog.

Remediation

The primary remediation is to upgrade GPAC MP4Box to a patched version released by the GPAC project after the June 2026 publication date. Organizations should verify the specific version number and availability in their distribution channels or from the official GPAC repository. Until a patch is available and deployed, restrict processing of MP4 files from untrusted sources and consider sandboxing MP4Box execution in isolated environments to limit the impact of crashes.

Patch guidance

Monitor the GPAC project's release notes and security advisories for a patched version that addresses the heap buffer overflow in gf_opus_parse_packet_header. Verify patch availability on the official GPAC GitHub repository or your vendor's patch portal. Once released, prioritize deployment across all systems running v2.4, particularly in automated media processing pipelines where crashes could cascade. Test patches in a staging environment first to confirm compatibility with your media workflows.

Detection guidance

Monitor for MP4Box crashes or segmentation faults in logs, especially when processing files from external or untrusted sources. Implement input validation on MP4 files before they reach MP4Box—check for malformed Opus headers or suspicious packet structures using media inspection tools. Network-based detection is limited since the attack is file-driven; focus instead on host-level monitoring of application crashes and system core dumps. Anomalous MP4 files with oversized or malformed Opus packets may be identifiable by dedicated media file analysis tools.

Why prioritize this

This vulnerability merits prompt but measured attention. While the CVSS 5.5 score is moderate, the low complexity of exploitation, lack of privilege requirements, and commonality of MP4 processing in modern workflows make it a practical concern. Organizations should patch promptly once updates are available, but this is not an emergency-level incident. Prioritization should be higher for environments that ingest media from untrusted partners, public sources, or automated systems. The absence of KEV listing indicates limited evidence of active exploitation in the wild, so there is reasonable time to plan and execute remediation without crisis-mode response.

Risk score, explained

The CVSS 5.5 (MEDIUM) score reflects the balance between exploitability factors and impact. The local attack vector and user interaction requirement constrain real-world attack surface compared to network-based flaws. However, the high availability impact (complete denial of service) and low attack complexity elevate risk for environments that depend on uninterrupted media processing. No confidentiality or integrity loss occurs, limiting the score further. Organizations with heavy MP4Box usage, especially in automated systems, should treat this as a higher priority within their patch cycle despite the moderate CVSS rating.

Frequently asked questions