Pillow: Out-of-bounds access in _imagingmorph on a zero-width image

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

8.7 · 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 · score source

EPSS

• CVE-2026-112397: 0.57% estimated exploitation activity in the next 30 days; percentile 47.38 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary A PPM or PGM file can declare a width of 0, which Pillow accepts, producing an image of size `(0, N)`. Passing that image to `ImageMorph.MorphOp.apply()` makes the native morphology code index a row buffer at `outrow[width - 1]`, which is `outrow[-1]` when the width is 0. The process crashes.

Details The PPM parser reads width and height with no lower-bound check: - `src/PIL/PpmImagePlugin.py:119` The native `apply()` writes the row edges with no guard that the width is positive: - `src/_imagingmorph.c:81` sets `outrow[0] = outrow[width - 1] = 0;` `match()` and `get_on_pixels()` use the same edge-indexing pattern.

PoC ```python from PIL import Image, ImageMorph

A width-0 image (also producible from a crafted PPM header). apply() indexes

outrow[width - 1] == outrow[-1] in native code. im = Image.new("L", (0, 5)) ImageMorph.MorphOp(op_name="dilation4").apply(im) ``` Run it: ``` $ python 03_poc.py Segmentation fault (core dumped) ``` Observed on a source build of…

Published by the source

20 Oct 2026, 20:56 UTC

Last modified by the source

29 Oct 2026, 10:45 UTC

Source last checked

30 Oct 2026, 07:20 UTC

1. Revision 10 · amended · 30 Oct 2026

   Amended from osv record BIT-pillow-2026-112397

2. Revision 9 · amended · 29 Oct 2026

   Amended from osv record BIT-pillow-2026-112397

3. Revision 8 · amended · 29 Oct 2026

   Amended from osv record PYSEC-2026-4329

4. Revision 7 · amended · 29 Oct 2026

   Amended from osv record GHSA-58r4-6rv3-gfh8

5. Revision 6 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-58r4-6rv3-gfh8

6. Revision 5 · amended · 26 Oct 2026

   Amended from osv record BIT-pillow-2026-112397

7. Revision 4 · amended · 26 Oct 2026

   Amended from osv record GHSA-58r4-6rv3-gfh8

8. Revision 3 · amended · 25 Oct 2026

   Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

9. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GHSA-58r4-6rv3-gfh8

10. Revision 1 · created · 23 Oct 2026

    Published from ghsa record GHSA-58r4-6rv3-gfh8

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# Patch Next advisory brief: CVE-2026-112397

Advisory: Pillow: Out-of-bounds access in _imagingmorph on a zero-width image
IDs: CVE-2026-112397, GHSA-58r4-6rv3-gfh8
Record: https://patchnext.com/advisories/cve-2026-112397 (revision 10, source checked 30 Oct 2026, 07:20 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: pillow 13.0.0; pillow 13.0.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Bitnami pillow: affected < 13.0.0; fixed in 13.0.0
- PyPI pillow: affected < 13.0.0; fixed in 13.0.0

## Suggested inspection (read-only)
- Bitnami pillow: check the installed version with your package manager.
- `python -m pip show pillow`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on pillow.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-58r4-6rv3-gfh8 (GitHub-reviewed advisory GHSA-58r4-6rv3-gfh8 lists affected ranges: PyPI pillow >=0 <=12.3.0)
- Verified: https://osv.dev/vulnerability/GHSA-58r4-6rv3-gfh8 (OSV record GHSA-58r4-6rv3-gfh8 lists affected ranges: PyPI pillow >=0 <13.0.0 (fixed))
- Verified: https://osv.dev/vulnerability/BIT-pillow-2026-112397 (OSV record BIT-pillow-2026-112397 lists affected ranges: Bitnami pillow >=0 <13.0.0 (fixed))
- Verified: https://osv.dev/vulnerability/PYSEC-2026-4329 (OSV record PYSEC-2026-4329 lists affected ranges: PyPI pillow >=0 <13.0.0 (fixed))

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