Out-of-bounds Read in Strukturag Libheif
CVE-2026-84451
libheif is a HEIF and AVIF file format decoder and encoder. From 1.19.0 until 1.23.3, the no-icef full-item branch of unc_decoder::get_compressed_image_data_uncompressed() in libheif/codecs/uncompressed/unc_decoder.cc retains an addition-based range check that can wrap when a crafted uncompressed tile grid produces a large range_start_offset and range_size. The overflow makes the bounds comparison pass and allows heif_image_handle_decode_image_tile() to call memcpy() with an invalid source pointer and a very large length when decoding a valid high-index advertised tile. This incomplete remediation of CVE-2026-62292 can reliably crash tile-processing applications, while whole-image decoding is not claimed to reach the demonstrated path. This issue is fixed in version 1.23.3.
Vulnerability class: Buffer Overflow
CVSS v3 metric
CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H.
Affected products
- Strukturag Libheif — versions >= 1.19.0, < 1.23.3
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_MISC)
- security-advisories@github.com (x_refsource_MISC)
- security-advisories@github.com (x_refsource_CONFIRM)
Frequently asked questions
- What is CVE-2026-84451?
- CVE-2026-84451 is a medium-severity vulnerability in Strukturag Libheif, classified under Out-of-bounds Read. CVSS score: 6.5/10. Published 2026-09-18.
- How severe is CVE-2026-84451?
- Medium severity. CVSS v3 base score is 6.5 out of 10.