# CVE-2026-84444: libheif heap buffer overflow in uncompressed encoder

Source: https://junglewise.ai/threats/cve-2026-84444-libheif-is-a-heif-and-avif-file-format-decoder-and-encoder-prior  
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-2026-84444 · Severity: high · CVSS 7.4 · Published 2026-09-18

libheif is a decoder and encoder for HEIF and AVIF image formats used by many applications to handle modern image files. When the uncompressed codec feature is enabled, an attacker can craft a malicious image file with incorrectly sized tile data that causes a heap buffer overflow, potentially leading to data corruption, information disclosure, or remote code execution.

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

## Quick answers

**Is CVE-2026-84444 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-84444 being exploited in the wild.

**How severe is CVE-2026-84444?** High severity, with a CVSS score of 7.4, published 18 September 2026.

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

**Is there a fix for CVE-2026-84444?** A patch was published on 2026-08-24. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-84444 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-84444?** 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

The vulnerability exists in the unci encoder's tile handling path when WITH_UNCOMPRESSED_CODEC is enabled. The heif_context_add_image_tile() function accepts independently constructed tiles whose component-plane dimensions do not match the tile geometry, and passes them to unc_encoder::encode_tile() which lacks validation and sizes its output buffer based on the prototype image's configuration while copying from the tile's actual dimensions, causing a heap buffer overflow. The fix adds comprehensive validation gates to encode_tile() that verify colorspace, chroma format, component properties, and plane sizes against the prototype before encoding.

## Affected products

- strukturag libheif before 1.23.2

## Timeline

- 2026-09-18: disclosed
- 2026-08-24: patched

## References

- [https://github.com/strukturag/libheif/commit/e65071f59a1ac08aa1eb0d07a831deaf6bb4d03b](https://github.com/strukturag/libheif/commit/e65071f59a1ac08aa1eb0d07a831deaf6bb4d03b)
- [https://github.com/strukturag/libheif/releases/tag/v1.23.2](https://github.com/strukturag/libheif/releases/tag/v1.23.2)

## Related threats

- [libheif heap buffer overflow in unc_decoder_mixed_interleave](https://junglewise.ai/threats/cve-2026-120208-libheif-1-18-0-before-1-23-3-contains-a-heap-based-buffer)
- [libheif integer overflow in uncompressed tile range check](https://junglewise.ai/threats/cve-2026-84451-libheif-is-a-heif-and-avif-file-format-decoder-and-encoder-from-1)
- [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)
- [libheif reference amplification denial of service](https://junglewise.ai/threats/cve-2026-84447-libheif-is-a-heif-and-avif-file-format-decoder-and-encoder-in-1)