# CVE-2026-84451: libheif integer overflow in uncompressed tile range check

Source: https://junglewise.ai/threats/cve-2026-84451-libheif-is-a-heif-and-avif-file-format-decoder-and-encoder-from-1  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-18. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-84451 · Severity: medium · CVSS 6.5 · Published 2026-09-18

libheif is a library that decodes and encodes HEIF and AVIF image formats. A flaw in the uncompressed tile decoder allows a maliciously crafted image to cause an integer overflow, leading to an out-of-bounds memory read that can crash applications processing individual image tiles. Whole-image decoding is not affected. The issue is fixed in version 1.23.3.

Technologies: [Strukturag Libheif](https://junglewise.ai/threats/technologies/strukturag-libheif). Vendors: [Strukturag](https://junglewise.ai/threats/vendors/strukturag).

## Quick answers

**Is CVE-2026-84451 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-84451 being exploited in the wild.

**How severe is CVE-2026-84451?** Medium severity, with a CVSS score of 6.5, published 18 September 2026.

**Which products and versions are affected?** Strukturag Libheif 1.19.0 through 1.23.2.

**Is there a fix for CVE-2026-84451?** A patch was published on 2026-09-01: Fixed in version 1.23.3 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-84451 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-84451?** Check whether you run Strukturag Libheif at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

An integer overflow in unc_decoder::get_compressed_image_data_uncompressed() allows range_start_offset + range_size to wrap in uint64_t arithmetic when processing a crafted uncompressed tile grid, bypassing bounds checking. This permits heif_image_handle_decode_image_tile() to call memcpy() with an invalid source pointer and excessive length, causing an out-of-bounds read. The vulnerability is triggered only in the no-icef full-item code path when decoding individual tiles via heif_image_handle_decode_image_tile().

## Affected products

- strukturag libheif 1.19.0 through 1.23.2

## Timeline

- 2026-09-18: disclosed
- 2026-09-01: patched: Fixed in version 1.23.3

## References

- [https://github.com/strukturag/libheif/commit/8bfed9a9ed008e4ef28abc736284a90d3cba754f](https://github.com/strukturag/libheif/commit/8bfed9a9ed008e4ef28abc736284a90d3cba754f)
- [https://github.com/strukturag/libheif/releases/tag/v1.23.3](https://github.com/strukturag/libheif/releases/tag/v1.23.3)

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- [libheif assertion failure in clap property crop calculation](https://junglewise.ai/threats/cve-2026-84450-libheif-is-a-heif-and-avif-file-format-decoder-and-encoder-from-1)
- [libheif heap out-of-bounds read in inline-mask region API](https://junglewise.ai/threats/cve-2026-84448-libheif-is-a-heif-and-avif-file-format-decoder-and-encoder-prior)
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- [libheif sequence timing denial of service and memory exhaustion](https://junglewise.ai/threats/cve-2026-84446-libheif-is-a-heif-and-avif-file-format-decoder-and-encoder-prior)