CVE-2026-22691— pypdf has possible long runtimes for malformed startxref
Quick assessment
Affected
py-pdf pypdf
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.
pypdf是py-pdf开源的一个免费开源的纯 python PDF 库。能够拆分、合并、裁剪和转换 PDF 文件的页面。 pypdf 6.6.0之前版本存在安全漏洞，该漏洞源于处理格式错误的startxref条目时可能产生长运行时间，可能导致拒绝服务。
Possible ATT&CK Techniques 1 AI
T1190 · Exploit Public-Facing Application
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I. Basic Information for CVE-2026-22691
Vulnerability Information
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Vulnerability Title
pypdf has possible long runtimes for malformed startxref
Source: CVE Program / CVE List V5
Vulnerability Description
pypdf is a free and open-source pure-python PDF library. Prior to version 6.6.0, pypdf has possible long runtimes for malformed startxref. An attacker who uses this vulnerability can craft a PDF which leads to possibly long runtimes for invalid startxref entries. When rebuilding the cross-reference table, PDF files with lots of whitespace characters become problematic. Only the non-strict reading mode is affected. Only the non-strict reading mode is affected. This issue has been patched in version 6.6.0.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U
Source: CVE Program / CVE List V5
Vulnerability Type
CWE-1333
Source: CVE Program / CVE List V5
Vulnerability Title
pypdf 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
pypdf是py-pdf开源的一个免费开源的纯 python PDF 库。能够拆分、合并、裁剪和转换 PDF 文件的页面。 pypdf 6.6.0之前版本存在安全漏洞，该漏洞源于处理格式错误的startxref条目时可能产生长运行时间，可能导致拒绝服务。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)
Affected Products
II. Public POCs for CVE-2026-22691
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Patches & Fixes for CVE-2026-22691 (1)
IV. Related Vulnerabilities
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Same weakness: CWE-1333
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V. Comments for CVE-2026-22691
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