# CVE-2026-96638: Pillow: BMP RLE decoder memory-amplification DoS via unbounded delta escape / absolute mode


- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 21 Oct 2026
- **Updated:** 28 Oct 2026
- **Also known as:** BIT-pillow-2026-96638, DEBIAN-CVE-2026-96638, ECHO-27bd-2fb5-e1ab, GHSA-24rc-8hj2-v98c, UBUNTU-CVE-2026-96638

## What is CVE-2026-96638?

CVE-2026-96638 is a medium-severity vulnerability in Python Pillow, published on 21 Oct 2026. 

### Official description

Pillow is a Python imaging library. From 9.1.0 until 13.0.0, BmpRleDecoder.decode() in src/PIL/BmpImagePlugin.py permits crafted RLE BMP delta escapes and absolute-mode runs to append beyond the remaining dest_length without a per-branch cap. A delta can add roughly 255 image rows in one iteration, so a kilobyte-sized file with a large but permitted width can expand the data bytearray to hundreds of megabytes or more, causing memory-exhaustion denial of service. This issue is fixed in version 13.0.0.

Weakness: CWE-770 (Allocation of Resources Without Limits or Throttling), CWE-400 (Uncontrolled Resource Consumption)

## Which versions are affected by CVE-2026-96638?

3 open source packages ship an affected version, including pillow. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `pillow` | Bitnami | From 9.1.0 | 13.0.0 |
| `pillow` | PyPI | From 9.1.0 | 13.0.0 |
| `pillow` | PyPI | From 9.1.0 | 13.0.0 |

Products: Python Pillow.

## How do I fix CVE-2026-96638?

Upgrade pillow to 13.0.0 or later.

## Is CVE-2026-96638 being exploited?

There is no known exploitation of CVE-2026-96638 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-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-2026-96638 and fix it if it is affected.

What it is: CVE-2026-96638 is a medium-severity vulnerability in Python Pillow, published on 21 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-96638 in the wild and no public exploit code.

Affected packages and fixed versions:
- pillow (Bitnami): affected from 9.1.0; fixed in 13.0.0
- pillow (PyPI): affected from 9.1.0; fixed in 13.0.0
- pillow (PyPI): affected from 9.1.0; 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-2026-96638/ (Markdown: https://insights.sbomify.com/CVE-2026-96638/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-96638
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-96638
- OSV: https://osv.dev/vulnerability/CVE-2026-96638

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-96638/
Summaries are generated and may contain mistakes; the official description above is the record.