# CVE-2026-96639: Pillow multi-frame loaders can reuse stale native image storage after mode transitions


- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 21 Oct 2026
- **Updated:** 29 Oct 2026
- **Also known as:** BIT-pillow-2026-96639, DEBIAN-CVE-2026-96639, ECHO-68a5-bb35-54de, GHSA-v9pv-5gc8-w2m6, PYSEC-2026-4339, ROOT-APP-PYPI-CVE-2026-96639, UBUNTU-CVE-2026-96639

## What is CVE-2026-96639?

CVE-2026-96639 is a critical vulnerability in Python Pillow, published on 21 Oct 2026. 

### Official description

Pillow is a Python imaging library. From 11.0.0 until 13.0.0, multi-frame loaders can retain an ImagingCore allocation created for a narrow frame mode while a later frame of the same dimensions changes the logical mode and decoder tiles to wider RGB or CMYK data. ImageFile.load_prepare() reuses the stale native storage because _im is non-null without verifying that its mode and size still match. Crafted PSD, MPO, DCX, or MIC frame transitions can then write wider pixels into the narrow allocation, causing native out-of-bounds writes and crashes. The MPO path can also cause a native over-read and, in demonstrated runtime-specific profiles, command execution. This issue is fixed in version 13.0.0.

Weakness: CWE-787 (Out-of-bounds Write), CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2026-96639?

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


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `pillow` | Bitnami | From 11.0.0 | 13.0.0 |
| `pillow` | PyPI | From 11.0.0 | 13.0.0 |
| `pillow` | PyPI | From 11.0.0 | 13.0.0 |
| `Pillow` | PyPI | From 11.0.0 | 13.0.0 |

Products: Python Pillow.

## How do I fix CVE-2026-96639?

Upgrade pillow to 13.0.0 or later.

## Is CVE-2026-96639 being exploited?

There is no known exploitation of CVE-2026-96639 in the wild and no public exploit code.

## Other vulnerabilities in Python Pillow

- [CVE-2014-3007](https://insights.sbomify.com/CVE-2014-3007/): Pillow command injection (critical 10.0)
- [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)
- [CVE-2026-112393](https://insights.sbomify.com/CVE-2026-112393/): Pillow: Heap buffer overflow in _tiffWriteProc when saving TIFF to BytesIO (critical 9.2)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-96639 and fix it if it is affected.

What it is: CVE-2026-96639 is a critical vulnerability in Python Pillow, published on 21 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-96639 in the wild and no public exploit code.

Affected packages and fixed versions:
- pillow (Bitnami): affected from 11.0.0; fixed in 13.0.0
- pillow (PyPI): affected from 11.0.0; fixed in 13.0.0
- pillow (PyPI): affected from 11.0.0; fixed in 13.0.0
- Pillow (PyPI): affected from 11.0.0; 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-2026-96639/ (Markdown: https://insights.sbomify.com/CVE-2026-96639/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-96639
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-96639
- OSV: https://osv.dev/vulnerability/CVE-2026-96639

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-96639/
Summaries are generated and may contain mistakes; the official description above is the record.