# CVE-2026-96644: Pillow: Heap over-read in WMF/EMF rendering via 16-bit dimension truncation (Windows builds)


- **Severity:** High 7.1 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 21 Oct 2026
- **Updated:** 28 Oct 2026
- **Also known as:** BIT-pillow-2026-96644, CLSA-2026-1793189478, ECHO-5bbc-7f9f-d028, GHSA-9v9v-9qvf-h2hj, PYSEC-2026-4343, ROOT-APP-PYPI-CVE-2026-96644, UBUNTU-CVE-2026-96644

## What is CVE-2026-96644?

CVE-2026-96644 is a high-severity vulnerability in Python Pillow, published on 21 Oct 2026. 

### Official description

Pillow is a Python imaging library. Prior to 13.0.0 on Windows, src/PIL/WmfImagePlugin.py passes unchecked 32-bit WMF or EMF dimensions to the native drawwmf handler in src/display.c. The handler sizes a DIB allocation from 16-bit-truncated bcWidth and bcHeight fields but copies pixel data using the original full dimensions. A crafted wide, short metafile can pass the pixel-count decompression-bomb check and make the Windows-only renderer read beyond the heap buffer, potentially disclosing memory or crashing the process. This issue is fixed in version 13.0.0.

Weakness: CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2026-96644?

4 open source packages ship an affected version, including pillow and Pillow. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `pillow` | Bitnami | All versions | 13.0.0 |
| `pillow` | PyPI | All versions | 13.0.0 |
| `pillow` | PyPI | All versions | 13.0.0 |
| `Pillow` | PyPI | All versions | 13.0.0 |

Products: Python Pillow.

## How do I fix CVE-2026-96644?

Upgrade pillow to 13.0.0 or later.

## Is CVE-2026-96644 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-96644 exists.

## Other vulnerabilities in Python Pillow

- [CVE-2014-3007](https://insights.sbomify.com/CVE-2014-3007/): Pillow command injection (critical 10.0)
- [CVE-2026-96639](https://insights.sbomify.com/CVE-2026-96639/): Pillow multi-frame loaders can reuse stale native image storage after mode transitions (critical 9.8)
- [CVE-2022-30595](https://insights.sbomify.com/CVE-2022-30595/): Buffer over-flow in Pillow (critical 9.8)
- [CVE-2021-25289](https://insights.sbomify.com/CVE-2021-25289/): Out of bounds write in Pillow (critical 9.8)
- [CVE-2016-4009](https://insights.sbomify.com/CVE-2016-4009/): Pillow Integer overflow in ImagingResampleHorizontal (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-96644 and fix it if it is affected.

What it is: CVE-2026-96644 is a high-severity vulnerability in Python Pillow, published on 21 Oct 2026. 
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-96644 exists.

Affected packages and fixed versions:
- pillow (Bitnami): affected all versions; fixed in 13.0.0
- pillow (PyPI): affected all versions; fixed in 13.0.0
- pillow (PyPI): affected all versions; fixed in 13.0.0
- Pillow (PyPI): affected all versions; fixed in 13.0.0

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-2026-96644/ (Markdown: https://insights.sbomify.com/CVE-2026-96644/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-96644
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-96644
- OSV: https://osv.dev/vulnerability/CVE-2026-96644

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-96644/
Summaries are generated and may contain mistakes; the official description above is the record.