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Medium, CVSS 6.3amended

Pillow: PdfParser can recurse without limit in get_value() and linearize_page_tree()

CVE-2026-112391GHSA-254f-3936-288h

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
    >= 5.1.0, < 13.0.0
    Fixed in
    13.0.0

  • PyPI pillow

    Affected
    >= 5.1.0, < 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
6.3 · CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N · score source
EPSS
  • CVE-2026-112391: 0.58% estimated exploitation activity in the next 30 days; percentile 47.80 (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 `PdfParser`'s `get_value()` can recurse without any limit and crash with an uncaught `RecursionError`. It is reachable through `Image.save(im, fp= , format="PDF", append=True)` when the existing PDF file is attacker-controlled. This is the same class of bug as https://github.com/advisories/GHSA-r73j-pqj5-w3x7 (the /Prev trailer chain loop, fixed earlier this year), in the same file, but in two different functions that fix did not touch.

Details `get_value()` in `src/PIL/PdfParser.py` This is a classmethod that takes `max_nesting: int = -1` and has a guard: ```python if max_nesting == 0: return None, None ``` Every recursive call (nested arrays, dictionaries, indirect object definitions) passes `max_nesting=max_nesting - 1`. Since the default and every call site start at -1, this only ever counts down further negative: -1, -2, -3, and so on. It never equals exactly 0, so the guard never runs. A PDF object with a value nested a few thousand levels deep is enough to…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 6 · amended ·

    Amended from ghsa record GHSA-254f-3936-288h

  2. Revision 5 · amended ·

    Amended from osv record BIT-pillow-2026-112391

  3. Revision 4 · amended ·

    Amended from osv record GHSA-254f-3936-288h

  4. Revision 3 · amended ·

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

  5. Revision 2 · amended ·

    Amended from osv record GHSA-254f-3936-288h

  6. Revision 1 · created ·

    Published from ghsa record GHSA-254f-3936-288h

Agent brief

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# Patch Next advisory brief: CVE-2026-112391

Advisory: Pillow: PdfParser can recurse without limit in get_value() and linearize_page_tree()
IDs: CVE-2026-112391, GHSA-254f-3936-288h
Record: https://patchnext.com/advisories/cve-2026-112391 (revision 6, source checked 26 Oct 2026, 13:55 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 >= 5.1.0, < 13.0.0; fixed in 13.0.0
- PyPI pillow: affected >= 5.1.0, < 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-254f-3936-288h (GitHub-reviewed advisory GHSA-254f-3936-288h lists affected ranges: PyPI pillow >=5.1.0 <13.0.0)
- Verified: https://osv.dev/vulnerability/GHSA-254f-3936-288h (OSV record GHSA-254f-3936-288h lists affected ranges: PyPI pillow >=5.1.0 <13.0.0 (fixed))
- Verified: https://osv.dev/vulnerability/BIT-pillow-2026-112391 (OSV record BIT-pillow-2026-112391 lists affected ranges: Bitnami pillow >=5.1.0 <13.0.0 (fixed))

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