# CVE-2026-84444: libheif uncompressed tiled image encoding allows out-of-bounds write

> An out-of-bounds write in libheif's uncompressed tiled image encoding allows attackers to execute arbitrary code when the uncompressed codec is enabled.

- **Severity:** High 7.4 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/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:** 22 Sep 2026
- **Also known as:** BELL-CVE-2026-84444, DEBIAN-CVE-2026-84444, ECHO-9fd0-a39b-9ef0, GHSA-j264-xvrp-5v7q, MINI-6vhc-mj8v-xw4c, ROOT-OS-DEBIAN-12-CVE-2026-84444

## What is CVE-2026-84444?

CVE-2026-84444 is a high-severity memory corruption 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, when WITH_UNCOMPRESSED_CODEC is enabled, heif_context_add_image_tile() accepts an independently constructed tile whose component-plane dimensions do not match the tile geometry established by the prototype image. ImageItem_uncompressed::add_image_tile() passes that tile directly to unc_encoder::encode_tile(), which lacked the check_component_sizes() gate and sizes its output from the configured tile geometry while copying the tile's actual component-plane dimensions. An oversized component plane can therefore make unc_encoder_component_interleave::encode_tile() copy attacker-controlled data beyond the heap output buffer. This issue is fixed in version 1.23.2.

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2026-84444?


## How do I fix CVE-2026-84444?

Upgrade to a fixed version.

## Is CVE-2026-84444 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-84444 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-84444 and fix it if it is affected.

What it is: CVE-2026-84444 is a high-severity memory corruption 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: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-84444 exists.

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-2026-84444/ (Markdown: https://insights.sbomify.com/CVE-2026-84444/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-84444
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-84444
- OSV: https://osv.dev/vulnerability/CVE-2026-84444

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-84444/
Summaries are generated and may contain mistakes; the official description above is the record.