# CVE-2026-84446: Denial of service in libheif

> Crafted HEIF files cause infinite loops and memory exhaustion in libheif, leading to denial of service.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 18 Sep 2026
- **Updated:** 21 Sep 2026
- **Also known as:** BELL-CVE-2026-84446, DEBIAN-CVE-2026-84446, ECHO-e3fa-3f8e-978c, GHSA-xw34-mjcp-jqh8, MINI-8fq3-gvvq-5q9f, ROOT-OS-DEBIAN-12-CVE-2026-84446, UBUNTU-CVE-2026-84446

## What is CVE-2026-84446?

CVE-2026-84446 is a high-severity denial of service vulnerability in strukturag libheif, published on 18 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

libheif is a HEIF and AVIF file format decoder and encoder. Prior to 1.23.2, crafted HEIF sequence timing and edit-list data can make Track::init_sample_timing_table() compute a logical m_num_output_samples value that exceeds the uint32_t counters used by Track_Visual::decode_next_image_sample() and Track::get_next_sample_raw_data(). The resulting comparison can never reach the oversized output count, causing non-terminating decode or raw-sample loops and bypassing max_sequence_frames. The same sequence path repeatedly calls Box_stts::get_sample_duration() and allocates Chunk::m_sample_ranges and Track::m_presentation_timeline outside MemoryHandle accounting, allowing severe CPU and memory exhaustion from a small file. This issue is fixed in version 1.23.2.

Weakness: CWE-835 (Loop with Unreachable Exit Condition)

## Which versions are affected by CVE-2026-84446?


## How do I fix CVE-2026-84446?

Upgrade to a fixed version.

## Is CVE-2026-84446 being exploited?

There is no known exploitation of CVE-2026-84446 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-84446 and fix it if it is affected.

What it is: CVE-2026-84446 is a high-severity denial of service vulnerability in strukturag libheif, published on 18 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-84446 in the wild and no public exploit code.

Affected product: strukturag libheif. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-84446/ (Markdown: https://insights.sbomify.com/CVE-2026-84446/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-84446
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-84446
- OSV: https://osv.dev/vulnerability/CVE-2026-84446

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-84446/
Summaries are generated and may contain mistakes; the official description above is the record.