# CVE-2026-96642: Pillow: TarIO negative size field causes infinite CPU-spin loop


- **Severity:** High 7.1 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 21 Oct 2026
- **Updated:** 21 Oct 2026
- **Also known as:** BIT-pillow-2026-96642, DEBIAN-CVE-2026-96642, ECHO-274d-5de4-fefd, GHSA-3j72-p6qg-6xp7, PYSEC-2026-4341, ROOT-APP-PYPI-CVE-2026-96642, UBUNTU-CVE-2026-96642

## What is CVE-2026-96642?

CVE-2026-96642 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, the TarIO initializer in src/PIL/TarIO.py accepts a negative octal member size and computes a backward seek that returns to the same 512-byte header. When the requested member name does not match, the parser repeatedly reads that header, consumes a full CPU core, and never returns. TarIO is reached only when an application directly uses PIL.TarIO.TarIO rather than the default Image.open() path. This issue is fixed in version 13.0.0.

Weakness: CWE-835 (Loop with Unreachable Exit Condition)

## Which versions are affected by CVE-2026-96642?

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-2026-96642?

Upgrade pillow to 13.0.0 or later.

## Is CVE-2026-96642 being exploited?

There is no known exploitation of CVE-2026-96642 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-2026-96642 and fix it if it is affected.

What it is: CVE-2026-96642 is a high-severity vulnerability in Python Pillow, published on 21 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-96642 in the wild and no public exploit code.

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-2026-96642/ (Markdown: https://insights.sbomify.com/CVE-2026-96642/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-96642
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-96642
- OSV: https://osv.dev/vulnerability/CVE-2026-96642

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-96642/
Summaries are generated and may contain mistakes; the official description above is the record.