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High, CVSS 8.7amended

Pillow: APNG background disposal allocates full canvas before decompression bomb check

CVE-2026-112399GHSA-5xm2-6676-qcp9

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (pillow 13.0.0; pillow 13.0.0), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

  • Bitnami pillow

    Affected
    >= 8.1.0, < 13.0.0
    Fixed in
    13.0.0

  • PyPI pillow

    Affected
    >= 8.1.0, < 13.0.0
    Fixed in
    13.0.0

Sources

Severity and exploitation
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-2026-112399: 0.53% estimated exploitation activity in the next 30 days; percentile 44.82 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

``` ============================================================================ APNG background disposal allocates full canvas before decompression bomb check Location: src/PIL/PngImagePlugin.py:1000 in PngImageFile._seek() Commit: a707c6b21c313880d0771e54965d142dd42358b6 ============================================================================ ``` A 126-byte animated PNG file makes Pillow's `Image.open()` allocate and fill memory sized by the image dimensions the file claims, before Pillow's built-in check for oversized images runs. A file claiming 22000×22000 pixels costs about 1.9 GB. Anyone who can get an application to open an image they supply, with default settings and no further calls such as `load()`, can cause a multi-gigabyte memory spike per file. If the claimed size exceeds the machine's free memory, the operating system kills the process outright. The bug is in `PngImageFile._seek()` in `src/PIL/PngImagePlugin.py` (around line 1000). For any APNG, `_open()` calls…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 7 · amended ·

    Amended from osv record BIT-pillow-2026-112399

  2. Revision 6 · amended ·

    Amended from ghsa record GHSA-5xm2-6676-qcp9

  3. Revision 5 · amended ·

    Amended from osv record BIT-pillow-2026-112399

  4. Revision 4 · amended ·

    Amended from osv record GHSA-5xm2-6676-qcp9

  5. Revision 3 · amended ·

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

  6. Revision 2 · amended ·

    Amended from osv record GHSA-5xm2-6676-qcp9

  7. Revision 1 · created ·

    Published from ghsa record GHSA-5xm2-6676-qcp9

Agent brief

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2026-112399

Advisory: Pillow: APNG background disposal allocates full canvas before decompression bomb check
IDs: CVE-2026-112399, GHSA-5xm2-6676-qcp9
Record: https://patchnext.com/advisories/cve-2026-112399 (revision 7, source checked 30 Oct 2026, 07:30 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 >= 8.1.0, < 13.0.0; fixed in 13.0.0
- PyPI pillow: affected >= 8.1.0, < 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-5xm2-6676-qcp9 (GitHub-reviewed advisory GHSA-5xm2-6676-qcp9 lists affected ranges: PyPI pillow >=8.1.0 <13.0.0)
- Verified: https://osv.dev/vulnerability/GHSA-5xm2-6676-qcp9 (OSV record GHSA-5xm2-6676-qcp9 lists affected ranges: PyPI pillow >=8.1.0 <13.0.0 (fixed))
- Verified: https://osv.dev/vulnerability/BIT-pillow-2026-112399 (OSV record BIT-pillow-2026-112399 lists affected ranges: Bitnami pillow >=8.1.0 <13.0.0 (fixed))

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