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High, CVSS 8.8amended

Pillow: TIFF encoder ColorMap plane-size mismatch causes a heap out-of-bounds read

CVE-2026-112896GHSA-pchr-8j38-3x4p

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
8.8 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N · score source
EPSS
  • CVE-2026-112896: 0.47% estimated exploitation activity in the next 30 days; percentile 41.08 (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 A small attacker-supplied TIFF can be opened and loaded normally, then reach an out-of-bounds read when an application saves it back to TIFF with retained metadata. The fixed reproducer is a 1×1, 16-bit grayscale, PackBits-compressed TIFF containing tag 320 (ColorMap) with 768 SHORT values: three zero-filled planes of 256 entries each. No Python object is forged and no metadata is injected after loading. Pillow's TIFF encoder allocates 768 × 2 = 1536 bytes, then passes three plane pointers separated by 256 SHORT entries to libtiff. With `BitsPerSample = 16`, libtiff instead expects 65536 SHORT values per plane and attempts a 131072-byte read from a plane pointer. Existing ASAN observations identify a heap-buffer-overflow READ crossing the 1536-byte allocation made in `PyImaging_LibTiffEncoderNew`. The malformed ColorMap need not be a valid palette for this grayscale image. The issue is that accepted metadata is forwarded on save without reconciling the…

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-2026-112896

  2. Revision 9 · amended ·

    Amended from osv record BIT-pillow-2026-112896

  3. Revision 8 · amended ·

    Amended from osv record PYSEC-2026-4334

  4. Revision 7 · amended ·

    Amended from osv record GHSA-pchr-8j38-3x4p

  5. Revision 6 · amended ·

    Amended from ghsa record GHSA-pchr-8j38-3x4p

  6. Revision 5 · amended ·

    Amended from osv record BIT-pillow-2026-112896

  7. Revision 4 · amended ·

    Amended from osv record GHSA-pchr-8j38-3x4p

  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-pchr-8j38-3x4p

  10. Revision 1 · created ·

    Published from ghsa record GHSA-pchr-8j38-3x4p

Agent brief

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# Patch Next advisory brief: CVE-2026-112896

Advisory: Pillow: TIFF encoder ColorMap plane-size mismatch causes a heap out-of-bounds read
IDs: CVE-2026-112896, GHSA-pchr-8j38-3x4p
Record: https://patchnext.com/advisories/cve-2026-112896 (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: High (CVSS 8.8)
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-pchr-8j38-3x4p (GitHub-reviewed advisory GHSA-pchr-8j38-3x4p lists affected ranges: PyPI pillow >=0 <=12.3.0)
- Verified: https://osv.dev/vulnerability/GHSA-pchr-8j38-3x4p (OSV record GHSA-pchr-8j38-3x4p lists affected ranges: PyPI pillow >=0 <13.0.0 (fixed))
- Verified: https://osv.dev/vulnerability/BIT-pillow-2026-112896 (OSV record BIT-pillow-2026-112896 lists affected ranges: Bitnami pillow >=0 <13.0.0 (fixed))
- Verified: https://osv.dev/vulnerability/PYSEC-2026-4334 (OSV record PYSEC-2026-4334 lists affected ranges: PyPI pillow >=0 <13.0.0 (fixed))

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