CVE-2025-0751: Axiosys Bento4 Buffer Overflow Vulnerability

CVE-2025-0751 Overview

CVE-2025-0751 is a heap-based buffer overflow vulnerability in Axiomatic Bento4 through version 1.6.0, an open-source C++ toolkit for MP4 media file processing. The flaw resides in the AP4_BitReader::ReadBits function within the mp42aac component, which extracts AAC audio streams from MP4 containers. An attacker can trigger the overflow by supplying a crafted media file, and the exploit details have been published. The issue is tracked under [CWE-119] and [CWE-787], covering improper memory buffer restrictions and out-of-bounds writes.

Critical Impact
A remote attacker can supply a malformed MP4 file to mp42aac and corrupt heap memory, leading to process crashes or potential code execution in workflows that process untrusted media.

Affected Products

Axiomatic Systems Bento4 versions up to and including 1.6.0
The mp42aac command-line utility shipped with Bento4
Downstream applications and pipelines that link the Bento4 library (axiosys:bento4)

Discovery Timeline

2025-01-27 - CVE-2025-0751 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-0751

Vulnerability Analysis

The vulnerability is a heap-based buffer overflow triggered inside AP4_BitReader::ReadBits, a helper used to consume variable-length bit fields from MP4 sample data. When mp42aac parses a crafted input, ReadBits reads beyond the allocated buffer that backs the bit reader, producing an out-of-bounds write on the adjacent heap region.

Because Bento4 is commonly invoked as a media processing utility on file uploads, transcoding servers, and forensic tooling, a single malformed MP4 file is sufficient to reach the vulnerable code path. The attack requires no authentication and no user interaction beyond opening or processing the file. The EPSS score is 0.484% at the 38.24 percentile, and no active exploitation has been confirmed by CISA.

Root Cause

The root cause is missing bounds validation between the requested bit count and the remaining size of the underlying byte buffer. AP4_BitReader::ReadBits advances an internal cursor based on attacker-controlled length fields parsed from the MP4 structure. When those fields exceed the buffer size, the function still writes and reads past the allocation, corrupting adjacent heap metadata and objects.

Attack Vector

The attack vector is network-adjacent through file delivery. An attacker hosts or transmits a malicious MP4 file and induces the target to process it with mp42aac, either directly or through an automated media pipeline. Successful exploitation crashes the process and can, depending on heap layout, be shaped into arbitrary code execution.

No verified proof-of-concept code is published in this advisory. Technical reproduction seeds are referenced in the Bento4 GitHub Issue #991 and VulDB entry #293517.

Detection Methods for CVE-2025-0751

Indicators of Compromise

Repeated crashes or segmentation faults in mp42aac or any process linking libAP4
MP4 files with malformed AAC sample tables submitted through upload endpoints or transcoding queues
Core dumps referencing AP4_BitReader::ReadBits in the stack trace

Detection Strategies

Instrument media processing hosts with AddressSanitizer or Valgrind during triage to confirm heap corruption in Bento4 code paths
Inventory systems for Bento4 binaries and libraries at version 1.6.0 or earlier using software composition analysis
Alert on unexpected child processes or shell spawns originating from media conversion workers

Monitoring Recommendations

Log all invocations of mp42aac with input file hashes and originating user or service account
Forward crash telemetry from media pipelines to a central SIEM for correlation with file upload events
Monitor for anomalous outbound connections from transcoding hosts that could indicate post-exploitation activity

How to Mitigate CVE-2025-0751

Immediate Actions Required

Identify all deployments of Axiomatic Bento4 1.6.0 and earlier across build servers, transcoding farms, and developer workstations
Restrict mp42aac execution to sandboxed environments with no network egress and minimal filesystem access
Reject or quarantine MP4 files from untrusted sources until a patched build is deployed

Patch Information

At the time of the last NVD update on 2026-06-17, no vendor-supplied patch release is referenced in the advisory. Track the upstream Bento4 GitHub Issue #991 for fix commits and rebuild affected binaries once a corrected version is published. Users who compile Bento4 from source should apply bounds checks in AP4_BitReader::ReadBits and re-run the reproducer seeds published with the issue.

Workarounds

Run mp42aac inside a container or seccomp-restricted profile that blocks execve and network syscalls
Pre-validate MP4 files with a stricter parser before passing them to Bento4
Disable the mp42aac code path in pipelines that do not require AAC extraction

bash

# Example: run mp42aac under a restrictive sandbox
firejail --net=none --private --read-only=/ \
         --caps.drop=all --nonewprivs --noroot \
         mp42aac /input/untrusted.mp4 /output/audio.aac