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  4. CVE 2026 96640 pillow pdf append accepts malformed shared page
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Back to active CVEs
High · CVSS 8.2CVE-2026-96640

Pillow PDF append accepts malformed shared page-tree DAG causing resource exhaustionCVE-2026-96640

Answer in brief

CVE-2026-96640 records a High severity (CVSS 8.2) vulnerability in Pillow PDF append accepts malformed shared page-tree DAG causing resource exhaustion. The current sources do not mark it as known exploited. The current feed maps python-pillow/Pillow (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Oct 21, 2026Updated Oct 21, 2026Source checked Oct 21, 2026First seen by HOL Oct 21, 2026Material review Oct 21, 2026
Upstream Advisory

Key facts

Risk
High · CVSS 8.2
Exploitation
Not marked as known exploited
Affected software
1 mapped package or product
Fix availability
Available

Why this deserves its current priority

CVSS is 8.2. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps python-pillow/Pillow (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
PackageAffected rangeFixed version
python-pillow/Pillowgeneric>=5.1.0 <13.0.013.0.0

Recommended response

  1. 1Check inventory. Check lockfiles and deployed manifests for python-pillow/Pillow.
  2. 2Review the reported fix. Update python-pillow/Pillow to 13.0.0 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

  1. Published upstream

    Oct 21, 2026

    Evidence: source:cvelist:source_dates:source-dates:record

  2. Source modified

    Oct 21, 2026

    Evidence: source:cvelist:source_dates:source-dates:record

  3. First seen by HOL

    Oct 21, 2026

Sources and claim methodology

  • GitHub security advisorygithub.com
  • GitHub security advisorygithub.com
  • GitHub security advisorygithub.com
  • GitHub security advisorygithub.com
Upstream source description

Pillow is a Python imaging library. From 5.1.0 until 13.0.0, PdfParser.linearize_page_tree() in src/PIL/PdfParser.py treats a PDF /Pages graph as a tree without tracking duplicate indirect references. When Image.save(..., format="PDF", append=True) processes an attacker-controlled existing PDF whose /Kids arrays repeatedly reference the same child /Pages node, Pillow expands the shared subtree as distinct pages. A compact malformed PDF can therefore create exponentially many page references and consume disproportionate CPU before the append completes. This issue is fixed in version 13.0.0.

Quoted source text, attributed separately from HOL analysis.

Related CVEs

  • Pillow: Arrow export leaks stale heap memory when PILLOW_ALIGNMENT > 1Same python-pillow/pillow package
  • Pillow: Decompression-bomb protection bypass via multi-frame seek() in MPO and DCX (MpoImageFile.seek / DcxImageFile.seek)Same python-pillow/pillow package
  • Pillow: Decompression bomb check bypass in SpiderImagePlugin.seek() leads to unbounded allocation DoSSame python-pillow/pillow package
  • Pillow: BMP RLE decoder memory-amplification DoS via unbounded delta escape / absolute modeSame python-pillow/pillow package
  • Pillow multi-frame loaders can reuse stale native image storage after mode transitionsSame python-pillow/pillow package
  • Pillow: Reachable undefined behavior in native integer operations, potentially leading to denial of service or logic integrity compromiseSame python-pillow/pillow package

Record context

Vulnerability class
Vulnerability
EPSS
Not reported
CWE IDs
CWE-400, CWE-407
Source
CVE List V5
Source checked
Oct 21, 2026
References
4 linked sources
Open source record