CVE-2026-113793: CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop') in py-pdf pypdf
Description
CVE-2026-113793 is a medium severity vulnerability in the py-pdf pypdf library prior to version 6.20.1. It involves an infinite loop triggered when removing an object from a crafted cyclic PDF tree, such as an outline item, which can block the current process. This issue has been fixed in version 6.20.1.
CVSS v4.0
Score 6.0medium
Affected software
py-pdf
pypdf
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The pypdf library, a pure-Python PDF processing tool, contained a vulnerability classified as CWE-835 (Loop with Unreachable Exit Condition) in versions before 6.20.1. When an object is removed from a specially crafted cyclic PDF tree structure, the code can enter an infinite loop, causing the process to hang indefinitely. This flaw was addressed and fixed in version 6.20.1.
Potential Impact
An attacker can craft a malicious PDF with a cyclic tree structure that, when processed by vulnerable versions of pypdf, causes the application to enter an infinite loop and become unresponsive. This results in a denial of service by blocking the current process. There is no indication of code execution or data corruption from the provided data.
Mitigation Recommendations
Upgrade pypdf to version 6.20.1 or later, where this infinite loop issue has been fixed. No other mitigation is required as the vendor has provided an official fix.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-10-20T17:39:41.373Z
- Cvss Version
- 4.0
- State
- PUBLISHED
Threat ID: 6ad8e5564d27ba8daac24090
Added to database: 10/21/2026, 16:16:22 UTC
Last enriched: 10/21/2026, 16:30:27 UTC
Last updated: 10/21/2026, 17:15:43 UTC
Views: 4
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