CVE-2026-90612: GPAC MP4Box Privilege Escalation Vulnerability

CVE-2026-90612 Overview

CVE-2026-90612 is a reachable assertion vulnerability [CWE-617] in GPAC, an open-source multimedia framework. The flaw resides in the gf_sm_dump_command_list function within scene_manager/scene_dump.c, part of the MP4Box component. A locally supplied crafted input triggers an assertion failure that terminates the process. The issue affects GPAC builds up to commit f1219cde and is resolved in release abi-16.23. Exploitation requires local access with low privileges and no user interaction. Public proof-of-concept information is available through the referenced advisory and issue tracker.

Critical Impact
Local attackers can trigger an assertion failure in MP4Box, causing a denial-of-service condition when processing malicious scene input.

Affected Products

GPAC multimedia framework up to commit f1219cde
GPAC MP4Box command-line utility
GPAC builds prior to release abi-16.23

Discovery Timeline

2026-09-14 - CVE-2026-90612 published to NVD
2026-09-14 - Last updated in NVD database

Technical Details for CVE-2026-90612

Vulnerability Analysis

The vulnerability is a reachable assertion [CWE-617] in GPAC's scene dumping code. The gf_sm_dump_command_list function in scene_manager/scene_dump.c fails to validate input state before invoking an assertion. When MP4Box processes a specially crafted scene or command list, the assertion evaluates to false and aborts the process. The impact is limited to availability, and the attack surface is local because MP4Box is a command-line tool that operates on files supplied by the invoking user. The referenced VulDB entry and CVE Summit report describe the trigger path through the scene dump routine.

Root Cause

The root cause is missing input validation prior to an assertion check. Rather than gracefully rejecting malformed command list data, the code relies on gf_assert to enforce structural invariants. Assertions compiled into release builds turn any malformed input into an abort. The maintainers addressed this class of issue in commit afca1f1181668d85941d51ed1adf647807d5d975, which replaces several assertions across fuzz-reachable paths with explicit error handling.

Attack Vector

Exploitation requires local access and the ability to invoke MP4Box against attacker-controlled input. An attacker crafts a scene file that reaches gf_sm_dump_command_list with state that violates the assertion. Processing the file terminates MP4Box, denying service to any workflow that depends on it. There is no path to code execution, information disclosure, or integrity impact reported for this issue.

// Patch pattern from commit afca1f1181668d85941d51ed1adf647807d5d975
// Replaces raw assertions with explicit validation and error return

// Before:
//   gf_assert(pck_data[0] == 0);
//   gf_assert(pck_data[1] == 0);
//   gf_assert(pck_data[2] == 1);

// After:
if (size < 3 || pck_data[0] != 0 || pck_data[1] != 0 || pck_data[2] != 1) {
    gf_filter_pid_drop_packet(ctx->ipid);
    gf_filter_pck_discard(dst_pck);
    return GF_BAD_PARAM;
}

gf_filter_pck_set_framing(dst_pck, GF_TRUE,
    (full_frame || ctx->input_is_au_end) ? GF_TRUE : GF_FALSE);
gf_filter_pck_set_cts(dst_pck, ctx->cts);

Source: GitHub Commit afca1f1

Detection Methods for CVE-2026-90612

Indicators of Compromise

Unexpected MP4Box process termination with assertion failure messages in stderr or system logs
Core dumps generated by MP4Box when processing untrusted scene or command list files
Repeated crashes of media processing pipelines invoking vulnerable GPAC builds

Detection Strategies

Inventory hosts running GPAC and compare installed versions against release abi-16.23 and commit afca1f1181668d85941d51ed1adf647807d5d975.
Monitor process exit codes and abort signals from MP4Box invocations in automated media pipelines.
Review file provenance for scene files fed into MP4Box on shared or multi-tenant systems.

Monitoring Recommendations

Forward process crash telemetry and core-dump events from build servers and media workers to a central logging pipeline.
Alert on repeated SIGABRT from MP4Box processes, which may indicate malformed input being replayed.
Track invocations of MP4Box against user-uploaded content and correlate with any subsequent process failures.

How to Mitigate CVE-2026-90612

Immediate Actions Required

Upgrade GPAC to release abi-16.23 or a build that includes commit afca1f1181668d85941d51ed1adf647807d5d975.
Restrict execution of MP4Box to trusted users and avoid running it against untrusted scene files.
Isolate media conversion workflows in sandboxed or containerized environments to contain crashes.

Patch Information

The fix is available in the GPAC ABI-16.23 release. The patch commit is afca1f1181668d85941d51ed1adf647807d5d975 and replaces reachable assertions with explicit input validation and error returns. Additional context is available in GitHub Issue #3821 and the CVE Summit Vulnerability Report.

Workarounds

Do not process untrusted or attacker-supplied scene files with vulnerable MP4Box builds.
Wrap MP4Box invocations in a supervisor that restarts the process on abnormal termination.
Apply filesystem and user-level access controls to limit who can supply input to MP4Box.

bash

# Verify installed GPAC version and upgrade from source to abi-16.23
MP4Box -version

git clone https://github.com/gpac/gpac.git
cd gpac
git checkout abi-16.23
./configure && make -j$(nproc)
sudo make install

# Confirm the fix commit is present
git log --oneline | grep afca1f1