CVE-2026-32740: struktur libheif Out-of-bounds Write

Vulnerability summary

CVE-2026-32740 is a high (CVSS 8.8) Out-of-bounds Write vulnerability in struktur libheif. EPSS estimates a 0.76% chance of exploitation in the next 30 days, higher than 54.4% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 19-05-2026
   PublishedVulnerability first disclosed.
2. 15-07-2026
   Last modifiedVulnerability information updated.

Description

libheif is a HEIF and AVIF file format decoder and encoder. Versions 1.21.2 and prior contain a heap-buffer-overflow (write) vulnerability in the grid tile compositing, allowing an attacker to write 64 bytes of fully attacker-controlled data past the end of a chroma plane heap allocation by crafting a HEIF/AVIF file with a 1×4 grid of odd-height tiles. The overflow is triggered during normal image decoding with default build configuration. The written bytes are chroma (Cb/Cr) pixel values from the attacking tile, giving the attacker full control over the overflow content. This issue has been fixed in version 1.22.0.

• CWE-787Out-of-bounds WriteThe product writes data past the end, or before the beginning, of the intended buffer.