# CVE-2026-84446: libheif sequence timing denial of service and memory exhaustion

Source: https://junglewise.ai/threats/cve-2026-84446-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-2026-84446 · Severity: high · CVSS 7.5 · Published 2026-09-18

libheif is a library for decoding and encoding HEIF and AVIF image files. Crafted HEIF files with malicious sequence timing and edit-list data can cause the decoder to enter non-terminating loops and allocate unbounded memory, allowing an attacker to exhaust CPU and memory resources from a small file. This vulnerability can be triggered by simply opening a malicious file in any application using the affected library.

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

## Quick answers

**Is CVE-2026-84446 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-84446 being exploited in the wild.

**How severe is CVE-2026-84446?** High severity, with a CVSS score of 7.5, published 18 September 2026.

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

**Is there a fix for CVE-2026-84446?** A patch was published on 2026-08-25: Fixed in libheif 1.23.2 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-84446 attacked?** It is attacked over the network or from the adjacent network, in a software library.

**Am I affected by CVE-2026-84446?** 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 Track::init_sample_timing_table(), which computes a logical m_num_output_samples value as a uint64 that can exceed uint32_t limits, but decode/raw-output loops use uint32 counters that can never reach the oversized count, causing non-terminating loops. Additionally, Box_stts::get_sample_duration() performs O(entries×samples) scans, and Chunk::m_sample_ranges and Track::m_presentation_timeline are allocated outside MemoryHandle accounting, allowing severe CPU and memory exhaustion. The attack vector is network/adjacent via opening a malicious HEIF/AVIF file; no authentication or user interaction beyond file opening is required.

## Affected products

- strukturag libheif before 1.23.2

## Timeline

- 2026-09-18: disclosed: CVE-2026-84446 published
- 2026-08-25: patched: Fixed in libheif 1.23.2

## References

- [https://github.com/strukturag/libheif/commit/3a7a69ae325f652e48c026b8241ab25bedf44d9b](https://github.com/strukturag/libheif/commit/3a7a69ae325f652e48c026b8241ab25bedf44d9b)
- [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)