What is CVE-2026-66038?

CVE-2026-66038 is a medium-severity vulnerability in Ffmpeg, classified under Use of Uninitialized Resource. CVSS score: 6.5/10. Published 2026-07-24.

How severe is CVE-2026-66038?

Medium severity. CVSS v3 base score is 6.5 out of 10.

Vulnerability in Ffmpeg

CVE-2026-66038

FFmpeg through 8.1.2, fixed in commit 8670835, contains an information disclosure vulnerability in the LCL/ZLIB video decoder that allows attackers to expose uninitialized heap memory by supplying a valid zlib stream that inflates to fewer…

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N.

Affected products

Ffmpeg — versions 0, 86708357d126af84c16f80d9c57335d1e8c845c5

Weakness classification (CWE)

CWE-908 — Use of Uninitialized Resource

References

disclosure@vulncheck.com (patch)
disclosure@vulncheck.com (issue-tracking)
disclosure@vulncheck.com (third-party-advisory)

Frequently asked questions

What is CVE-2026-66038?: CVE-2026-66038 is a medium-severity vulnerability in Ffmpeg, classified under Use of Uninitialized Resource. CVSS score: 6.5/10. Published 2026-07-24.
How severe is CVE-2026-66038?: Medium severity. CVSS v3 base score is 6.5 out of 10.