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Critical, CVSS 9.2amended

Pillow: Heap buffer overflow in ImagingJpegDecode

CVE-2026-112403GHSA-8g5g-8vmr-9782

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
    < 13.0.0
    Fixed in
    13.0.0

  • PyPI pillow

    Affected
    < 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
9.2 · CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N · score source
EPSS
  • CVE-2026-112403: 0.95% estimated exploitation activity in the next 30 days; percentile 61.12 (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.

Summary `JpegImageFile.draft()` — which `Image.thumbnail()` calls automatically — requests 1/2, 1/4 or 1/8 scaled JPEG output and shrinks `self._size` and the tile extents to match, so `_setimage()` allocates a single-row decode buffer of `ceil(W/s)` samples. `ImagingJpegDecode()` sets `cinfo.scale_num`/`scale_denom`, calls `jpeg_start_decompress()`, and then reads scanlines into that buffer without ever comparing `cinfo.output_width`, `cinfo.output_height` or `cinfo.out_color_components` against `state->xsize`, `state->ysize` and `state->bits`. libjpeg-turbo 3.x decodes lossless (SOF3) JPEG, but hardwires lossless streams to no scaling — the requested `scale_denom` is silently discarded. It therefore returns full-width `W`-sample rows into a buffer sized for `ceil(W/s)`. Each `jpeg_read_scanlines()` call writes `(W - ceil(W/s)) x components` bytes past the end of the heap allocation, and the overflowing bytes are the decoded pixel values, which are byte-exact for an 8-bit…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 10 · amended ·

    Amended from osv record BIT-pillow-2026-112403

  2. Revision 9 · amended ·

    Amended from osv record BIT-pillow-2026-112403

  3. Revision 8 · amended ·

    Amended from osv record PYSEC-2026-4332

  4. Revision 7 · amended ·

    Amended from osv record GHSA-8g5g-8vmr-9782

  5. Revision 6 · amended ·

    Amended from ghsa record GHSA-8g5g-8vmr-9782

  6. Revision 5 · amended ·

    Amended from osv record BIT-pillow-2026-112403

  7. Revision 4 · amended ·

    Amended from osv record GHSA-8g5g-8vmr-9782

  8. Revision 3 · amended ·

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

  9. Revision 2 · amended ·

    Amended from osv record GHSA-8g5g-8vmr-9782

  10. Revision 1 · created ·

    Published from ghsa record GHSA-8g5g-8vmr-9782

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-2026-112403

Advisory: Pillow: Heap buffer overflow in ImagingJpegDecode
IDs: CVE-2026-112403, GHSA-8g5g-8vmr-9782
Record: https://patchnext.com/advisories/cve-2026-112403 (revision 10, 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: Critical (CVSS 9.2)
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-8g5g-8vmr-9782 (GitHub-reviewed advisory GHSA-8g5g-8vmr-9782 lists affected ranges: PyPI pillow >=0 <=12.3.0)
- Verified: https://osv.dev/vulnerability/GHSA-8g5g-8vmr-9782 (OSV record GHSA-8g5g-8vmr-9782 lists affected ranges: PyPI pillow >=0 <13.0.0 (fixed))
- Verified: https://osv.dev/vulnerability/BIT-pillow-2026-112403 (OSV record BIT-pillow-2026-112403 lists affected ranges: Bitnami pillow >=0 <13.0.0 (fixed))
- Verified: https://osv.dev/vulnerability/PYSEC-2026-4332 (OSV record PYSEC-2026-4332 lists affected ranges: PyPI pillow >=0 <13.0.0 (fixed))

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