CVE-2026-96640
Published:October 21, 2026
Updated:October 22, 2026
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.
Affected Packages
pillow (CONDA):
Affected version(s) >=5.1.0 <13.0.0Fix Suggestion:
Update to version 13.0.0https://github.com/python-pillow/Pillow.git (GITHUB):
Affected version(s) >=12.0.0 <13.0.0Fix Suggestion:
Update to version 13.0.0pillow (PYTHON):
Affected version(s) >=5.1.0 <13.0.0Fix Suggestion:
Update to version 13.0.0pillow (PYTHON):
Affected version(s) >=12.0.0 <13.0.0Fix Suggestion:
Update to version 13.0.0Related Resources (7)
Do you need more information?
Contact UsCVSS v4
Base Score:
8.2
Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
PRESENT
Privileges Required
NONE
User Interaction
NONE
Vulnerable System Confidentiality
NONE
Vulnerable System Integrity
NONE
Vulnerable System Availability
HIGH
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
7.5
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Weakness Type (CWE)
EPSS
Base Score:
0.42