CVE-2026-66040
Heap OOB in FFmpeg PNG/APNG encoder allows potential RCE via crafted eXIf PNG.
Is CVE-2026-66040 being exploited?
Not confirmed. CVE-2026-66040 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.51% probability of exploitation in the next 30 days.
How severe is CVE-2026-66040?
CVE-2026-66040 is rated High with a CVSS score of 8.7. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-66040?
Yes. A fix has been recorded for CVE-2026-66040. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-66040 affect?
CVE-2026-66040 affects FFmpeg ≤ 8.1.2 (PNG/APNG encoders), Applications using FFmpeg for PNG/APNG encoding. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-66040?
Upgrade FFmpeg to commit b506faf or later; avoid processing untrusted PNGs.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Crafted PNG eXIf chunks can cause deterministic heap corruption during encoding, enabling crashes and potential arbitrary code execution remotely.
Immediate action required
- affected<= 8.1.2
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.