CVE-2026-47251: Struktur Libheif

Medium severity, CVSS 6.1. EPSS: 0.2% chance of exploitation in the next 30 days.

libheif is a HEIF and AVIF file format decoder and encoder. The fix for CVE-2026-3949 (commit `b97c8b5`, PR #1712) introduced an integer overflow in the very security check it added. The check itself can be bypassed, allowing a crafted HEIF file with a VVC track to trigger the same out-of-bounds heap read that CVE-2026-3949 was meant to prevent. This is a separate, currently-unpatched vulnerability. Issue #1712 was closed as fixed without testing the edge case where `size` is near `UINT32_MAX`. Version 1.22.0 patches the issue.

Affected products

• Struktur Libheif: before 1.22.0 (fixed in 1.22.0)

Published 2026-07-21. Last modified 2026-07-27.