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Critical, CVSS 9.2amended

Pillow: Heap buffer overflow in _tiffWriteProc when saving TIFF to BytesIO

CVE-2026-112393GHSA-332p-7hrc-92wf

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
    >= 2.0.0, < 13.0.0
    Fixed in
    13.0.0

  • PyPI pillow

    Affected
    >= 2.0.0, < 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
9.2 · CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N · score source
EPSS
  • CVE-2026-112393: 1.02% estimated exploitation activity in the next 30 days; percentile 63.43 (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.

``` ============================================================================ Heap buffer overflow in _tiffWriteProc when saving TIFF to BytesIO Location: src/libImaging/TiffDecode.c:94 in _tiffWriteProc() Commit: a707c6b21c313880d0771e54965d142dd42358b6 ============================================================================ ``` Pillow can write attacker-chosen data past the end of a heap buffer when it saves a TIFF image to an in-memory destination such as `io.BytesIO` rather than to a file. The same code also copies leftover heap memory from the process into the saved file. Anyone who can supply an image to a service that opens it and re-saves it as TIFF this way can trigger this with default settings. The attached reproducer crashes the process, and the overflow could potentially be developed further, but code execution is not demonstrated here. The bug is in `_tiffWriteProc` in `src/libImaging/TiffDecode.c`. This is the write callback for the in-memory sink that Pillow…

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-2026-112393

  2. Revision 6 · amended ·

    Amended from ghsa record GHSA-332p-7hrc-92wf

  3. Revision 5 · amended ·

    Amended from osv record BIT-pillow-2026-112393

  4. Revision 4 · amended ·

    Amended from osv record GHSA-332p-7hrc-92wf

  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-332p-7hrc-92wf

  7. Revision 1 · created ·

    Published from ghsa record GHSA-332p-7hrc-92wf

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-2026-112393

Advisory: Pillow: Heap buffer overflow in _tiffWriteProc when saving TIFF to BytesIO
IDs: CVE-2026-112393, GHSA-332p-7hrc-92wf
Record: https://patchnext.com/advisories/cve-2026-112393 (revision 7, 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: 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 >= 2.0.0, < 13.0.0; fixed in 13.0.0
- PyPI pillow: affected >= 2.0.0, < 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-332p-7hrc-92wf (GitHub-reviewed advisory GHSA-332p-7hrc-92wf lists affected ranges: PyPI pillow >=2.0.0 <13.0.0)
- Verified: https://osv.dev/vulnerability/GHSA-332p-7hrc-92wf (OSV record GHSA-332p-7hrc-92wf lists affected ranges: PyPI pillow >=2.0.0 <13.0.0 (fixed))
- Verified: https://osv.dev/vulnerability/BIT-pillow-2026-112393 (OSV record BIT-pillow-2026-112393 lists affected ranges: Bitnami pillow >=2.0.0 <13.0.0 (fixed))

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