Vulnerability · Published Aug 18, 2026 · Assigned by GitHub_M
CVE-2026-62289libheif: Integer underflow in Fraction constructor via double clap transform application
Medium 4.3
In plain English
A medium-severity security flaw in libheif from strukturag. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 23% 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. In 1.23.0 and earlier, a crafted HEIF or AVIF file containing a clean aperture box can reduce an image dimension to zero and crash or corrupt tiling results when heif_image_handle_get_image_tiling(handle, 1, &tiling) is called. ImageItem::get_heif_image_tiling() returns already transformed dimensions, and process_image_transformations_on_tiling() applies the clean aperture transformation again. The second application passes zero to Box_clap::left_rounded(0), where image_width minus one underflows and constructs Fraction(0xFFFFFFFF, 2). Debug builds reach an assertion and abort, while release builds can return a corrupt crop and zero-width tiling result. The affected implementation spans libheif/image-items/image_item.cc, libheif/context.cc, and libheif/box.cc. This issue is fixed in version 1.23.1.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | libheif | no fix listed | DEBIAN-CVE-2026-62289 |
| Debian:13 | libheif | 1.19.8-1+deb13u1 | DEBIAN-CVE-2026-62289 |
| Debian:14 | libheif | 1.23.1-1 | DEBIAN-CVE-2026-62289 |
| Ubuntu:24.04:LTS | libheif | 1.17.6-1ubuntu4.7 | UBUNTU-CVE-2026-62289 |
| Ubuntu:24.04:LTS | libheif | 1.17.6-1ubuntu4.8 | USN-8683-1 |
| Ubuntu:26.04:LTS | libheif | 1.21.2-3ubuntu0.4 | UBUNTU-CVE-2026-62289 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| strukturag | libheif | < 1.23.1 |
Weakness: CWE-191, CWE-617 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L