Vulnerability · Published Sep 18, 2026 · Assigned by GitHub_M
CVE-2026-84448libheif: Heap out-of-bounds read in libheif inline-mask region API (heif_region_item_add_region_inline_mask_data / heif_region_get_mask_image)
Medium 4.0
In plain English
A medium-severity out-of-bounds read in libheif from strukturag. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 8% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
libheif is a HEIF and AVIF file format decoder and encoder. Prior to 1.23.2, the public heif_region_item_add_region_inline_mask_data() function in libheif/api/libheif/heif_regions.cc accepts mask_data_len without verifying that it equals the byte count required by width and height. A later heif_region_get_mask_image() call derives the read length from the region geometry, so an undersized stored buffer causes heif_region_get_inline_mask_image() to read beyond the heap allocation and copy adjacent bytes into the returned monochrome mask image. This can disclose heap data or crash an application that constructs region metadata through the writer API, while the file-parsing path is not affected because it validates the canonical mask size. This issue is fixed in version 1.23.2.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | libheif | no fix listed | DEBIAN-CVE-2026-84448 |
| Debian:13 | libheif | 1.23.4-1~deb13u1 | DEBIAN-CVE-2026-84448 |
| Debian:14 | libheif | 1.23.2-1 | DEBIAN-CVE-2026-84448 |
| Ubuntu:24.04:LTS | libheif | 1.17.6-1ubuntu4.9 | USN-8846-1 |
| Ubuntu:24.04:LTS | libheif | 1.17.6-1ubuntu4.9 | UBUNTU-CVE-2026-84448 |
| Ubuntu:26.04:LTS | libheif | 1.21.2-3ubuntu0.6 | USN-8846-1 |
| Ubuntu:26.04:LTS | libheif | 1.21.2-3ubuntu0.6 | UBUNTU-CVE-2026-84448 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| strukturag | libheif | < 1.23.2 |
Weakness: CWE-125, CWE-131 · Vector: CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:L