CVE-2026-48156: CWE-834: Excessive Iteration in py-pdf pypdf
pypdf is a free and open-source pure-python PDF library. Prior to 6.12.0, an attacker who uses this vulnerability can craft a PDF which leads to long runtimes. This requires cross-reference streams with /W [0 0 0] values and large /Size values. This vulnerability is fixed in 6.12.0.
AI Analysis
Technical Summary
The vulnerability CVE-2026-48156 affects pypdf, a pure-Python PDF library, in versions before 6.12.0. An attacker can create a malicious PDF with cross-reference streams that have /W [0 0 0] and large /Size values, causing the library to perform excessive iteration and resulting in prolonged processing times. This is classified under CWE-834 (Excessive Iteration). The vulnerability does not require user interaction or privileges and has a CVSS 4.0 base score of 5.1, indicating medium severity. There is no indication of known exploits in the wild. The issue is resolved in version 6.12.0.
Potential Impact
The impact of this vulnerability is primarily performance degradation due to long runtimes when processing specially crafted PDFs. It does not involve privilege escalation, code execution, or data leakage based on the provided information. No known active exploitation has been reported.
Mitigation Recommendations
Upgrade to pypdf version 6.12.0 or later, where this vulnerability is fixed. Since the vendor advisory confirms the fix in 6.12.0, applying this official update is the recommended remediation. No additional mitigation steps are indicated.
CVE-2026-48156: CWE-834: Excessive Iteration in py-pdf pypdf
Description
pypdf is a free and open-source pure-python PDF library. Prior to 6.12.0, an attacker who uses this vulnerability can craft a PDF which leads to long runtimes. This requires cross-reference streams with /W [0 0 0] values and large /Size values. This vulnerability is fixed in 6.12.0.
CVSS v4.0
Score 5.1medium
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability CVE-2026-48156 affects pypdf, a pure-Python PDF library, in versions before 6.12.0. An attacker can create a malicious PDF with cross-reference streams that have /W [0 0 0] and large /Size values, causing the library to perform excessive iteration and resulting in prolonged processing times. This is classified under CWE-834 (Excessive Iteration). The vulnerability does not require user interaction or privileges and has a CVSS 4.0 base score of 5.1, indicating medium severity. There is no indication of known exploits in the wild. The issue is resolved in version 6.12.0.
Potential Impact
The impact of this vulnerability is primarily performance degradation due to long runtimes when processing specially crafted PDFs. It does not involve privilege escalation, code execution, or data leakage based on the provided information. No known active exploitation has been reported.
Mitigation Recommendations
Upgrade to pypdf version 6.12.0 or later, where this vulnerability is fixed. Since the vendor advisory confirms the fix in 6.12.0, applying this official update is the recommended remediation. No additional mitigation steps are indicated.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-05-20T23:12:43.031Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a186056e29bf47b500b42cd
Added to database: 5/28/2026, 3:33:42 PM
Last enriched: 5/28/2026, 3:50:20 PM
Last updated: 5/29/2026, 8:21:23 AM
Views: 9
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