# CVE-2026-32740: libheif: Heap-Buffer-Overflow Write in Grid Tile Chroma Compositing

> An attacker can execute arbitrary code or cause a denial of service by crafting a malicious HEIF/AVIF file that triggers a heap buffer overflow in libheif.

- **Severity:** High 8.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 19 May 2026
- **Updated:** 15 Jul 2026
- **Also known as:** ALPINE-CVE-2026-32740, BELL-CVE-2026-32740, DEBIAN-CVE-2026-32740, ECHO-dba8-54f3-0eb4, GHSA-frfr-f3vg-2g6j, JLSEC-2026-572, ROOT-OS-DEBIAN-11-CVE-2026-32740, ROOT-OS-DEBIAN-12-CVE-2026-32740, UBUNTU-CVE-2026-32740

## What is CVE-2026-32740?

CVE-2026-32740 is a high-severity memory corruption vulnerability in strukturag libheif, published on 19 May 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

libheif is a HEIF and AVIF file format decoder and encoder. Versions 1.21.2 and prior contain a heap-buffer-overflow (write) vulnerability in the grid tile compositing, allowing an attacker to write 64 bytes of fully attacker-controlled data past the end of a chroma plane heap allocation by crafting a HEIF/AVIF file with a 1×4 grid of odd-height tiles. The overflow is triggered during normal image decoding with default build configuration. The written bytes are chroma (Cb/Cr) pixel values from the attacking tile, giving the attacker full control over the overflow content. This issue has been fixed in version 1.22.0.

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

## Which versions are affected by CVE-2026-32740?

It affects 1 product.


Products: Struktur Libheif.

## How do I fix CVE-2026-32740?

Upgrade to a fixed version.

## Is CVE-2026-32740 being exploited?

There is no known exploitation of CVE-2026-32740 in the wild and no public exploit code.

Public exploit code:

- Private Fortbridge PoC for the CVE-2026-32740 Next.js/sharp leak-to-memcpy-GOT RCE chain (github_poc): https://github.com/FORTBRIDGE-UK/libheif-grid-nextjs-rce

## Other vulnerabilities in strukturag libheif

- [CVE-2023-49460](https://insights.sbomify.com/CVE-2023-49460/): Null dereference in n/a (high 8.8)
- [CVE-2023-49462](https://insights.sbomify.com/CVE-2023-49462/): Null dereference in n/a (high 8.8)
- [CVE-2023-49463](https://insights.sbomify.com/CVE-2023-49463/): Null dereference in n/a (high 8.8)
- [CVE-2023-49464](https://insights.sbomify.com/CVE-2023-49464/): Null dereference in n/a (high 8.8)
- [CVE-2020-19498](https://insights.sbomify.com/CVE-2020-19498/): Denial of service in n/a (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-32740 and fix it if it is affected.

What it is: CVE-2026-32740 is a high-severity memory corruption vulnerability in strukturag libheif, published on 19 May 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-32740 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-2026-32740/ (Markdown: https://insights.sbomify.com/CVE-2026-32740/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-32740
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-32740
- OSV: https://osv.dev/vulnerability/CVE-2026-32740

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-32740/
Summaries are generated and may contain mistakes; the official description above is the record.