Vulnerability · Published Aug 18, 2026 · Assigned by GitHub_M
CVE-2026-50142libheif: unbounded heap allocation in HEIF sequence parser (stsz fixed-size mode missing bound check)
High 7.5
In plain English
A high-severity integer overflow 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 0.7% (higher than 52% of all known vulnerabilities). Ready-made attack tooling exists: public proof-of-concept code. 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 1.23.0, a crafted HEIF sequence accepted by heif_context_read_from_memory() with the msf1 sequence brand can cause unbounded heap allocation. In libheif/sequences/seq_boxes.cc, Box_stsz::parse() applies max_sequence_frames only to variable-size samples, so fixed-size mode accepts an attacker-controlled sample_count without a bound. In libheif/sequences/track.cc, Track::load() also adds current_sample_idx and samples_per_chunk in 32-bit arithmetic, allowing the consistency check to be bypassed by wraparound. The resulting values reach the Chunk::Chunk() allocation path, which can consume gigabytes of memory and crash or stall the process through memory exhaustion. This issue is fixed in version 1.23.0.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine:v3.23 | libheif | 1.23.0-r0 | ALPINE-CVE-2026-50142 |
| Alpine:v3.24 | libheif | 1.23.0-r0 | ALPINE-CVE-2026-50142 |
| Debian:12 | libheif | no fix listed | DEBIAN-CVE-2026-50142 |
| Debian:14 | libheif | 1.23.1-1 | DEBIAN-CVE-2026-50142 |
| Ubuntu:25.10 | libheif | 1.20.2-1ubuntu0.6 | UBUNTU-CVE-2026-50142 |
| Ubuntu:26.04:LTS | libheif | 1.21.2-3ubuntu0.3 | UBUNTU-CVE-2026-50142 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| strukturag | libheif | >= 1.19.0, < 1.23.0 |
Weakness: CWE-190, CWE-770 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H