CVE-2026-54531: 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 6.13.0, an attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This requires merging a file with outlines into a writer. This vulnerability is fixed in 6.13.0.
AI Analysis
Technical Summary
The vulnerability identified as CVE-2026-54531 affects the pypdf library, a pure-Python PDF processing tool. Versions before 6.13.0 contain a loop with an unreachable exit condition (CWE-835) that can be triggered by merging a PDF file containing outlines into a writer object. This crafted PDF can cause the process to enter an infinite loop, potentially leading to denial of service. The vulnerability has a CVSS 4.0 score of 6.9 (medium severity). The issue is resolved in pypdf version 6.13.0.
Potential Impact
An attacker who can supply a specially crafted PDF to an application using pypdf versions prior to 6.13.0 can cause the application to enter an infinite loop during PDF merging operations. This can result in denial of service by exhausting CPU resources or causing the application to hang. There is no indication of privilege escalation, data disclosure, or code execution from this vulnerability.
Mitigation Recommendations
Upgrade pypdf to version 6.13.0 or later, where this infinite loop vulnerability is fixed. No other mitigations are indicated. Patch status is confirmed fixed in 6.13.0.
CVE-2026-54531: 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 6.13.0, an attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This requires merging a file with outlines into a writer. This vulnerability is fixed in 6.13.0.
CVSS v4.0
Score 6.9medium
Affected software
Run on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability identified as CVE-2026-54531 affects the pypdf library, a pure-Python PDF processing tool. Versions before 6.13.0 contain a loop with an unreachable exit condition (CWE-835) that can be triggered by merging a PDF file containing outlines into a writer object. This crafted PDF can cause the process to enter an infinite loop, potentially leading to denial of service. The vulnerability has a CVSS 4.0 score of 6.9 (medium severity). The issue is resolved in pypdf version 6.13.0.
Potential Impact
An attacker who can supply a specially crafted PDF to an application using pypdf versions prior to 6.13.0 can cause the application to enter an infinite loop during PDF merging operations. This can result in denial of service by exhausting CPU resources or causing the application to hang. There is no indication of privilege escalation, data disclosure, or code execution from this vulnerability.
Mitigation Recommendations
Upgrade pypdf to version 6.13.0 or later, where this infinite loop vulnerability is fixed. No other mitigations are indicated. Patch status is confirmed fixed in 6.13.0.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-06-15T18:40:01.651Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a39a0f5eed863c81e6b01fa
Added to database: 06/22/2026, 20:54:13 UTC
Last enriched: 06/29/2026, 21:52:22 UTC
Last updated: 08/04/2026, 12:46:13 UTC
Views: 71
Community Reviews
0 reviewsCrowdsource mitigation strategies, share intel context, and vote on the most helpful responses. Sign in to add your voice and help keep defenders ahead.
Want to contribute mitigation steps or threat intel context? Sign in or create an account to join the community discussion.
Actions
Updates to AI analysis require Pro Console access. Upgrade inside Console → Billing.
Need more coverage?
Upgrade to Pro Console for AI refresh and higher limits.
For incident response and remediation, OffSeq services can help resolve threats faster.
Latest Threats
Check if your credentials are on the dark web
Instant breach scanning across billions of leaked records. Free tier available.