CVE-2026-66039: Heap Overflow (CVSS 8.8)

Description

FFmpeg through 8.1.2, fixed in commit aafb5c6, contains a signed integer overflow vulnerability in the MACE6 audio decoder that allows attackers to corrupt heap memory by supplying a crafted CAF file with a malicious bytes_per_packet value. Attackers can craft a CAF file with oversized bytes_per_packet and frames_per_packet values in the desc chunk to trigger an integer overflow in mace_decode_frame() during output sample count computation, resulting in an undersized buffer allocation and heap out-of-bounds write that could enable code execution.

Is your site exposed to CVE-2026-66039?

Run a free security scan — no signup, results in seconds.

CVSS v3.1 Score

8.8

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

EPSS — Exploit Prediction

0.0042

Probability of exploitation

0.35%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-122 CWE-122

CWE-190 Integer Overflow

References

Other References

https://code.ffmpeg.org/FFmpeg/FFmpeg/commit/aafb5c655edc76a753275c383ebb139feb032718 https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/23631 https://www.vulncheck.com/advisories/ffmpeg-mace6-audio-decoder-heap-out-of-bounds-write-via-caf-file

Frequently Asked Questions

What is CVE-2026-66039? +

FFmpeg through 8.1.2, fixed in commit aafb5c6, contains a signed integer overflow vulnerability in the MACE6 audio decoder that allows attackers to corrupt heap memory by supplying a crafted CAF file with a malicious bytes_per_packet value. Attackers can craft a CAF file with oversized bytes_per_packet and frames_per_packet values in the desc chunk to trigger an integer overflow in mace_decode_frame() during output sample count computation, resulting in an undersized buffer allocation and heap out-of-bounds write that could enable code execution. It has a CVSS v3.1 base score of 8.8 (HIGH).

How severe is CVE-2026-66039? +

CVE-2026-66039 has a CVSS v3.1 score of 8.8 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0042, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-66039? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

Related Vulnerabilities

CVE-2026-8997

vifm is vulnerable to a heap buffer overflow during the history merge process when saving the state file (vifminfo.json). This …

CVE-2026-8484

A heap buffer overflow vulnerability exists in the Jansi JNI "ioctl()" wrapper due to a lack of size verification for …

CVE-2026-6210

A type confusion vulnerability in Qt SVG allows an attacker to cause an application crash via a crafted SVG image. …

CVE-2026-2467

Heap-based Buffer Overflow vulnerability in RTI Connext Professional (Core Libraries) allows Overflow Variables and Tags.This issue affects Connext Professional: from …

CVE-2025-0633

Heap-based Buffer Overflow vulnerability in iniparser_dumpsection_ini() in iniparser allows attacker to read out of bound memory

CVE-2025-3512

There is a Heap-based Buffer Overflow vulnerability in QTextMarkdownImporter. This requires an incorrectly formatted markdown file to be passed to …

CVE-2026-66039