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

highCVSS 8.8CVE-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.

Details

Source: NVD Recent CVEs (US · database · site)
Severity: high — CVSS 8.8
Published: 2026-07-24
Last updated: 2026-07-29
Exploitation: Not in CISA KEV at last sync

Original advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-66039

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Low exploitation riskCVE-2026-660390.42% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 35% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-66039	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

high[NEW] [high] ffmpeg: Multiple vulnerabilitiescert-bund

Recent advisories for FFmpeg

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

highCVE-2026-67290: FreeRDP before 3.29.0 contains a heap out-of-bounds read vulnerability in the TSMF FFmpeg deco…nvd · 2026-08-01
high[UPDATE] [high] ffmpeg: Vulnerability allows code execution and Denial of Servicecert-bund · 2026-07-31
high[NEW] [high] ffmpeg: Multiple vulnerabilitiescert-bund · 2026-07-27
medium[UPDATE] [medium] ffmpeg: Vulnerability allows Denial of Servicecert-bund · 2026-07-27
highCVE-2026-66041: FFmpeg 7.0 through 8.1.2, fixed in commit 4da9812, contains a heap out-of-bounds write vulnera…nvd · 2026-07-24
highCVE-2026-66040: FFmpeg through 8.1.2, fixed in commit b506faf, contains a heap out-of-bounds write vulnerabili…nvd · 2026-07-24