Vulnerability · Published Sep 18, 2026 · Assigned by GitHub_M
CVE-2026-84450libheif: `clap` + oversized `ispe` aborts on an assert in `Fraction::Fraction` (incomplete fix for CVE-2026-62289)
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 21% 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. From 1.19.0 until 1.23.3, a crafted image item containing a clap property and an ispe width or height greater than INT32_MAX + 1 can reach crop calculations through heif_image_handle_get_image_tiling(). Box_clap::left_rounded() or Box_clap::top_rounded() passes the image dimension minus one to Fraction::Fraction(), whose uint32_t constructor uses an assertion as input validation, causing assert-enabled builds to abort. Release builds can instead compute invalid crop geometry, and the tiling API returns dimensions that the normal decode security limits reject. This issue is fixed in version 1.23.3.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | libheif | no fix listed | DEBIAN-CVE-2026-84450 |
| Debian:13 | libheif | 1.23.4-1~deb13u1 | DEBIAN-CVE-2026-84450 |
| Debian:14 | libheif | 1.23.3-1 | DEBIAN-CVE-2026-84450 |
| Ubuntu:24.04:LTS | libheif | no fix listed | UBUNTU-CVE-2026-84450 |
| Ubuntu:26.04:LTS | libheif | no fix listed | UBUNTU-CVE-2026-84450 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| strukturag | libheif | >= 1.19.0, < 1.23.3 |
Weakness: CWE-617 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L