# CVE-2026-32739: Strukturag libheif infinite loop in Box_stts::get_sample_duration

Source: https://junglewise.ai/threats/cve-2026-32739-strukturag-libheif-infinite-loop-in-box-stts-get-sample-duration  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-05-19. Updated: 2026-05-19  
License: CC BY 4.0 with a link back

CVE-2026-32739 · Severity: medium · CVSS 6.5 · Published 2026-05-19

libheif is a widely used software library for encoding and decoding HEIF and AVIF image files. A vulnerability in the way it parses certain image sequences allows a specially crafted, small file (as small as 800 bytes) to trap the software in an infinite loop. This causes the affected application to consume 100% of the CPU indefinitely without crashing or logging an error. In a business context, this can lead to a silent Denial of Service (DoS), where image processing servers or applications become unresponsive, potentially halting operations or exhausting cloud computing resources without triggering standard crash-monitoring alerts.

Technologies: [struktur AG Libheif](https://junglewise.ai/threats/technologies/libheif). Vendors: [struktur AG](https://junglewise.ai/threats/vendors/struktur-ag).

## Quick answers

**Is CVE-2026-32739 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-32739 being exploited in the wild.

**How severe is CVE-2026-32739?** Medium severity, with a CVSS score of 6.5, published 19 May 2026.

**Which products and versions are affected?** struktur AG Libheif <= 1.21.2.

**Is there a fix for CVE-2026-32739?** A patch was published on 2026-05-19: Version 1.22.0 released Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-32739 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-32739?** Check whether you run struktur AG 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 infinite loop vulnerability exists in libheif versions 1.21.2 and earlier within the Box_stts::get_sample_duration() and Box_ctts::get_sample_offset() functions in libheif/sequences/seq_boxes.cc. The root cause is a missing loop increment variable; when a crafted HEIF file contains a 'stts' (sample-to-time) box entry with a sample_count of zero, the loop fails to progress while the exit condition remains unfulfilled. An attacker can bypass library consistency checks by providing multiple entries that sum to a valid total. The vulnerability is triggered during the initial file parsing phase (heif_context_read_from_file) before any image decoding or user interaction occurs. This results in a permanent hang of the process with 100% CPU utilization and no error logs, effectively bypassing crash-based monitoring systems. The issue is resolved in version 1.22.0.

## Affected products

- strukturag libheif <= 1.21.2

## Timeline

- 2026-05-19: advisory: GHSA-j9g7-q9hv-gq8c published
- 2026-05-19: patched: Version 1.22.0 released
- 2026-05-19: disclosed: CVE-2026-32739 published to NVD

## References

- [https://github.com/strukturag/libheif/releases/tag/v1.22.0](https://github.com/strukturag/libheif/releases/tag/v1.22.0)
- [https://github.com/strukturag/libheif/security/advisories/GHSA-j9g7-q9hv-gq8c](https://github.com/strukturag/libheif/security/advisories/GHSA-j9g7-q9hv-gq8c)

## Related threats

- [libheif decompression bomb via brotli/zlib metadata](https://junglewise.ai/threats/cve-2026-84384-libheif-is-a-heif-and-avif-file-format-decoder-and-encoder-from-1)
- [Strukturag libheif heap OOB read in ImageItem_Grid::decode_grid_tile](https://junglewise.ai/threats/cve-2026-48029-strukturag-libheif-heap-oob-read-in-imageitem-grid-decode-grid)
- [Strukturag libheif integer overflow in region.cc mask parsing](https://junglewise.ai/threats/cve-2026-47714-strukturag-libheif-integer-overflow-in-region-cc-mask-parsing)
- [Strukturag libheif heap buffer over-read in SampleAuxInfoReader](https://junglewise.ai/threats/cve-2026-41071-strukturag-libheif-heap-buffer-over-read-in-sampleauxinforeader)
- [Strukturag libheif out-of-bounds read in SampleAuxInfoReader](https://junglewise.ai/threats/cve-2026-41069-strukturag-libheif-out-of-bounds-read-in-sampleauxinforeader)