CVE-2026-47247: libheif Vulnerable to Heap Information Disclosure via Grid Image Gap + Uninitialized Pixel Plane Allocation
libheif is a HEIF and AVIF file format decoder and encoder. Prior to version 1.22.0, two bugs in libheif chain to leak process heap memory as visible pixel values in decoded grid images. An attacker who uploads a crafted AVIF/HEIC file to any server-side image processor (WordPress, Sharp/libvips, ImageMagick, etc.) can recover heap data - including library function pointers sufficient to defeat ASLR, or any other secret - from the publicly-downloadable transcoded JPEG/PNG/WebP output. Local attack vectors are also possible. Version 1.22.0 fixes the issue.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
libheifto a version that resolves this vulnerability.Fixed in 1.22.0
Event History
Frequently Asked Questions
What is the severity of CVE-2026-47247?
CVE-2026-47247 has a high severity rating of 7.5.
What does CVE-2026-47247 affect?
CVE-2026-47247 affects the libheif library used for decoding and encoding HEIF and AVIF file formats.
How do I fix CVE-2026-47247?
To fix CVE-2026-47247, upgrade to libheif version 1.22.0 or later.
What type of vulnerability is CVE-2026-47247?
CVE-2026-47247 is classified as an information leak vulnerability.
What do the specific attack vectors for CVE-2026-47247 involve?
CVE-2026-47247 can be exploited by uploading a crafted AVIF/HEIC file to vulnerable server-side image processors.