# CVE-2026-84384: libheif decompression bomb via brotli/zlib metadata

Source: https://junglewise.ai/threats/cve-2026-84384-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-2026-84384 · Severity: high · CVSS 7.5 · Published 2026-09-18

libheif is a decoder and encoder for HEIF and AVIF image formats. A crafted image file with compressed metadata can cause the library to decompress data without size limits, consuming unbounded memory and crashing the application. An attacker can create a small malicious image file that triggers this denial-of-service when opened.

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

## Quick answers

**Is CVE-2026-84384 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-84384 being exploited in the wild.

**How severe is CVE-2026-84384?** High severity, with a CVSS score of 7.5, published 18 September 2026.

**Which products and versions are affected?** struktur AG Libheif 1.19.0 to 1.23.1.

**Is there a fix for CVE-2026-84384?** A patch was published on 2026-08-24: Fix committed to master branch Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-84384 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-84384?** 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

The vulnerability exists in decompress_brotli() and do_inflate() functions which lack effective output-size bounds. The brotli path has no output limit, while the zlib path only checks a small temporary buffer in a code branch that valid streams do not reach. Additionally, overlapping ICEF units can decompress the same payload repeatedly, amplifying memory consumption. HeifContext::interpret_heif_file_images() processes multiple compressed metadata items during file opening, allowing an attacker-crafted file to exhaust memory during the parse phase.

## Affected products

- Struktur AG libheif 1.19.0 to 1.23.1

## Timeline

- 2026-09-18: disclosed: CVE-2026-84384 published
- 2026-08-24: patched: Fix committed to master branch
- 2026-08-25: patched: Version 1.23.2 released with security fix

## References

- [https://github.com/strukturag/libheif/commit/21893e8f66c8b79363ca2809391b07d35e1a95ec](https://github.com/strukturag/libheif/commit/21893e8f66c8b79363ca2809391b07d35e1a95ec)
- [https://github.com/strukturag/libheif/releases/tag/v1.23.2](https://github.com/strukturag/libheif/releases/tag/v1.23.2)

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