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 the py-pdf pypdf library versions before 6.12.0. An attacker can craft a PDF file with cross-reference streams specifying /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 issue was resolved in pypdf version 6.12.0.
Potential Impact
The impact of this vulnerability is a denial of service condition through resource exhaustion, as processing a maliciously crafted PDF can cause long runtimes. There is no indication of code execution, privilege escalation, or data disclosure. No known exploits are reported in the wild.
Mitigation Recommendations
Upgrade to pypdf version 6.12.0 or later, where this vulnerability has been fixed. Patch status is confirmed by the version fix note. No additional mitigations are specified.
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
Affected software
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability CVE-2026-48156 affects the py-pdf pypdf library versions before 6.12.0. An attacker can craft a PDF file with cross-reference streams specifying /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 issue was resolved in pypdf version 6.12.0.
Potential Impact
The impact of this vulnerability is a denial of service condition through resource exhaustion, as processing a maliciously crafted PDF can cause long runtimes. There is no indication of code execution, privilege escalation, or data disclosure. No known exploits are reported in the wild.
Mitigation Recommendations
Upgrade to pypdf version 6.12.0 or later, where this vulnerability has been fixed. Patch status is confirmed by the version fix note. No additional mitigations are specified.
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: 05/28/2026, 15:33:42 UTC
Last enriched: 06/04/2026, 20:48:43 UTC
Last updated: 07/31/2026, 19:22:59 UTC
Views: 63
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