CVE-2026-54651: CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop') in py-pdf pypdf
pypdf is a free and open-source pure-python PDF library. Prior to 6.13.1, an attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This requires merging a file with threads/articles into a writer. This vulnerability is fixed in 6.13.1.
AI Analysis
Technical Summary
The pypdf library versions before 6.13.1 contain a vulnerability classified as CWE-835 (Loop with Unreachable Exit Condition), where processing a maliciously crafted PDF file with threads or articles can cause an infinite loop during file merging. This can lead to denial of service by exhausting processing resources. The vulnerability has a CVSS 4.0 base score of 6.9, indicating medium severity. The issue is fixed in pypdf version 6.13.1.
Potential Impact
An attacker can cause a denial of service condition by supplying a specially crafted PDF that triggers an infinite loop in the pypdf library when merging files with threads or articles. This can result in resource exhaustion and application unavailability. There is no indication of privilege escalation, code execution, or data disclosure.
Mitigation Recommendations
Upgrade to pypdf version 6.13.1 or later, where this infinite loop vulnerability is fixed. No other mitigation or workaround is documented. Patch status is confirmed by the vendor advisory indicating the fix in version 6.13.1.
CVE-2026-54651: CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop') in py-pdf pypdf
Description
pypdf is a free and open-source pure-python PDF library. Prior to 6.13.1, an attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This requires merging a file with threads/articles into a writer. This vulnerability is fixed in 6.13.1.
CVSS v4.0
Score 6.9medium
Affected software
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The pypdf library versions before 6.13.1 contain a vulnerability classified as CWE-835 (Loop with Unreachable Exit Condition), where processing a maliciously crafted PDF file with threads or articles can cause an infinite loop during file merging. This can lead to denial of service by exhausting processing resources. The vulnerability has a CVSS 4.0 base score of 6.9, indicating medium severity. The issue is fixed in pypdf version 6.13.1.
Potential Impact
An attacker can cause a denial of service condition by supplying a specially crafted PDF that triggers an infinite loop in the pypdf library when merging files with threads or articles. This can result in resource exhaustion and application unavailability. There is no indication of privilege escalation, code execution, or data disclosure.
Mitigation Recommendations
Upgrade to pypdf version 6.13.1 or later, where this infinite loop vulnerability is fixed. No other mitigation or workaround is documented. Patch status is confirmed by the vendor advisory indicating the fix in version 6.13.1.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-06-15T20:16:46.198Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a39a0f6eed863c81e6b0291
Added to database: 06/22/2026, 20:54:14 UTC
Last enriched: 07/10/2026, 09:50:24 UTC
Last updated: 08/05/2026, 00:41:15 UTC
Views: 117
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