# CVE-2026-112898: Pillow information disclosure in quantize with empty palette

Source: https://junglewise.ai/threats/cve-2026-112898-pillow-is-a-python-imaging-library-from-9-1-0-until-13-0-0  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-19. Updated: 2026-10-19  
License: CC BY 4.0 with a link back

CVE-2026-112898 · Severity: medium · CVSS 4 · Published 2026-10-19

Pillow is a Python image processing library used in web applications and image manipulation tools. When the quantize() function is called with an empty palette, uninitialized stack memory containing sensitive data like addresses and security tokens can be leaked in the returned image file. An attacker who controls the palette image can extract this information, potentially aiding in bypassing memory protections or other attacks.

Technologies: [pillow (PyPI)](https://junglewise.ai/threats/technologies/pillow), [Python Pillow Pillow](https://junglewise.ai/threats/technologies/python-pillow-pillow). Vendors: [PyPI](https://junglewise.ai/threats/vendors/pypi), [Python Pillow](https://junglewise.ai/threats/vendors/python-pillow).

## Quick answers

**Is CVE-2026-112898 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-112898 being exploited in the wild.

**How severe is CVE-2026-112898?** Medium severity, with a CVSS score of 4, published 19 October 2026.

**Which products and versions are affected?** pillow (PyPI) >= 9.1.0, < 13.0.0, ECOSYSTEM:introduced=9.1.0,fixed=13.0.0; Python Pillow Pillow 9.1.0 to 12.x.x.

**Is there a fix for CVE-2026-112898?** Yes. pillow (PyPI): upgrade to 13.0.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-112898 attacked?** It is attacked over the network or with local access.

**Am I affected by CVE-2026-112898?** Check whether you run pillow (PyPI) or Python Pillow Pillow at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- pillow (PyPI): upgrade to 13.0.0 or later

  ```sh
  pip install "pillow>=13.0.0"
  ```


## Technical details

The ImagingPaletteCacheUpdate() function in Pillow's image quantization path fails to initialize a local cache array when the palette has zero entries, leaving stack memory uninitialized. This uninitialized data is then emitted as output pixel indices in the converted image. The vulnerability can be triggered by calling Image.quantize() with an empty palette, and requires no out-of-bounds access, memory corruption, or crash.

## Affected products

- Python Pillow Pillow 9.1.0 to 12.x.x

## Identifiers

- CVE-2026-112898
- GHSA-rfgq-q3w2-pmv2

## Timeline

- 2026-10-19: disclosed

## References

- [https://github.com/python-pillow/Pillow/commit/13943c8f857b22f073d30f0ef9b725a0d255f1a4](https://github.com/python-pillow/Pillow/commit/13943c8f857b22f073d30f0ef9b725a0d255f1a4)
- [https://github.com/python-pillow/Pillow/releases/tag/13.0.0](https://github.com/python-pillow/Pillow/releases/tag/13.0.0)

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