CVE-2026-84448 Information disclosure in libheif
An attacker can trigger a heap out-of-bounds read in libheif's region API, potentially disclosing sensitive memory or crashing the application.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-84448?
CVE-2026-84448 is a medium-severity vulnerability in strukturag libheif, published on 18 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
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.
Which versions are affected by CVE-2026-84448?
How do I fix CVE-2026-84448?
Upgrade to a fixed version.
Is CVE-2026-84448 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-84448 exists.
Sources
Also known as BELL-CVE-2026-84448, DEBIAN-CVE-2026-84448, ECHO-93e0-e371-957b, GHSA-p58j-h3vm-3fp5, MINI-qv33-x58q-2qcv, UBUNTU-CVE-2026-84448.