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Medium, CVSS 6.3amended

Pillow: P;2L and P;4L decoders may read 1 to 3 bytes past the passed buffer size

CVE-2026-112394GHSA-4558-3h8r-v8xp

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
6.3 · CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:L/SC:N/SI:N/SA:N · score source
EPSS
  • CVE-2026-112394: 0.56% estimated exploitation activity in the next 30 days; percentile 46.34 (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 On `main`, even with the guard in #9725, it's possible to have these decoders read 1 to 3 bytes past the end of the passed buffer with a suitable width/height.

Details `ImagingRawDecode` and the `P;2L` / `P;4L` unpackers disagree about how many bytes a line of data occupies. The raw decoder derives the line size from the bits per pixel ```c state->bytes = (state->xsize * state->bits + 7) / 8; ``` and uses it both for the bounds check and to advance to the next line. For `P;2L` and `P;4L`, `bits` is 2 and 4 respectively. But these two rawmodes are not packed pixels but 2 or 4 *bit planes*, each padded to a whole number of bytes. `unpackP2L` computes `s = (pixels + 7) / 8` and reads plane *k* at offset `k * s`, and `unpackP4L` does the same across four planes. Their real footprint is therefore `planes * ((xsize + 7) / 8)`. For some widths, padding each plane separately makes this footprint larger than `state->bytes`. For example, at width 1, the decoder accounts for one…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 9 · amended ·

    Amended from osv record BIT-pillow-2026-112394

  2. Revision 8 · amended ·

    Amended from osv record PYSEC-2026-4327

  3. Revision 7 · amended ·

    Amended from osv record GHSA-4558-3h8r-v8xp

  4. Revision 6 · amended ·

    Amended from ghsa record GHSA-4558-3h8r-v8xp

  5. Revision 5 · amended ·

    Amended from osv record BIT-pillow-2026-112394

  6. Revision 4 · amended ·

    Amended from osv record GHSA-4558-3h8r-v8xp

  7. Revision 3 · amended ·

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

  8. Revision 2 · amended ·

    Amended from osv record GHSA-4558-3h8r-v8xp

  9. Revision 1 · created ·

    Published from ghsa record GHSA-4558-3h8r-v8xp

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-2026-112394

Advisory: Pillow: P;2L and P;4L decoders may read 1 to 3 bytes past the passed buffer size
IDs: CVE-2026-112394, GHSA-4558-3h8r-v8xp
Record: https://patchnext.com/advisories/cve-2026-112394 (revision 9, source checked 28 Oct 2026, 06:45 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.3)
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-4558-3h8r-v8xp (GitHub-reviewed advisory GHSA-4558-3h8r-v8xp lists affected ranges: PyPI pillow >=0 <=12.3.0)
- Verified: https://osv.dev/vulnerability/GHSA-4558-3h8r-v8xp (OSV record GHSA-4558-3h8r-v8xp lists affected ranges: PyPI pillow >=0 <13.0.0 (fixed))
- Verified: https://osv.dev/vulnerability/BIT-pillow-2026-112394 (OSV record BIT-pillow-2026-112394 lists affected ranges: Bitnami pillow >=0 <13.0.0 (fixed))
- Verified: https://osv.dev/vulnerability/PYSEC-2026-4327 (OSV record PYSEC-2026-4327 lists affected ranges: PyPI pillow >=0 <13.0.0 (fixed))

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