CVE-2026-66039: FFmpeg FFmpeg

FFmpeg MACE6 Audio Decoder Heap Out-of-Bounds Write via CAF File

CVSS 8.7 HighEPSS 0.0031 · 23rd percentile

Published by the CVE Program (CNA: VulnCheck) at 24 Jul 2026, 19:42 UTC. agentprime has not analysed this yet, so whether it affects any app is not known. This CVE names a vendor and product rather than a package, so the lockfile check doesn’t match it.

Affected products, as the CNA wrote them
Vendor	Product	Versions
FFmpeg	FFmpeg	affected 8.1.2 and earlier semver unaffected aafb5c655edc76a753275c383ebb139feb032718 git Other versions: affected

Identifiers

CVE-2026-66039

CNA

VulnCheck

Weakness (CWE)

CWE-122 · CWE-190

Not analysed yet

We haven’t published our own analysis of this CVE. If a person reviews it, this page will say what’s affected and what has to be true for it to matter.

Severity and exploitation

Score	Rating	CVSS	Vector	Source
8.7	High	4.0	CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N	CNA (VulnCheck)Used for this record
8.8	High	3.1	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H	CNA (VulnCheck)

CISA KEV Not listed.
EPSS 0.0031, the 23rd percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

This record came from the full history of the CVE Program, published 24 Jul 2026. New records show when each source confirmed them.

Sources

References from the CNA

code.ffmpeg.org/FFmpeg/FFmpeg/pulls/23631 issue-tracking
code.ffmpeg.org/FFmpeg/FFmpeg/commit/aafb5c655edc76a753275c383ebb139feb032718 patch
www.vulncheck.com/advisories/ffmpeg-mace6-audio-decoder-heap-out-of-bounds-write-via-caf-file third-party-advisory

Facts on this page come from the CVE List as the CNA published them, with CVSS from the sources named above, CISA KEV and FIRST EPSS. Vendors, products and versions are shown as the CNA wrote them. We don’t reproduce the CVE’s description.