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CVE-2026-84309— pypdf: Possible infinite loop for TreeObject.insert_child

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.

py-pdf pypdf是py-pdf组织开源的一款PDF文档处理组件。 pypdf 6.16.0之前版本存在资源管理错误漏洞，该漏洞源于PDF的循环树结构导致TreeObject.insert_child在写入代码路径插入子节点时无限跟踪/Next链接，产生无限循环。

CVSS 6.9 · Medium EPSS 0.19% · P8

Possible ATT&CK Techniques 1 AI

T1024

Affected Version Matrix 1

VendorProduct Version RangeStatus
py-pdf pypdf < 6.16.0 affected
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I. Basic Information for CVE-2026-84309

Vulnerability Information
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Vulnerability Title
pypdf: Possible infinite loop for TreeObject.insert_child
Source: CVE Program / CVE List V5
Vulnerability Description
pypdf is a free and open-source pure-python PDF library. Prior to 6.16.0, an attacker can craft a PDF whose cyclic tree structure causes pypdf/generic/_data_structures.py TreeObject.insert_child to follow /Next links indefinitely when a writing code path inserts a child, producing an infinite loop. This issue is fixed in version 6.16.0.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Source: CVE Program / CVE List V5
Vulnerability Type
不可达退出条件的循环(无限循环)
Source: CVE Program / CVE List V5
Vulnerability Title
pypdf 资源管理错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
py-pdf pypdf是py-pdf组织开源的一款PDF文档处理组件。 pypdf 6.16.0之前版本存在资源管理错误漏洞，该漏洞源于PDF的循环树结构导致TreeObject.insert_child在写入代码路径插入子节点时无限跟踪/Next链接，产生无限循环。
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

Vendor Product Affected Versions CPE Subscribe
py-pdf pypdf < 6.16.0 -

II. Public POCs for CVE-2026-84309

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III. Intelligence Information for CVE-2026-84309

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Patches & Fixes for CVE-2026-84309 (2)

Vendor Advisories for CVE-2026-84309 (1)

Vendor Pages for CVE-2026-84309 (1)

Same Patch Batch · py-pdf · 2026-09-01 · 3 CVEs total

CVE-2026-84310 4.8 MEDIUM pypdf: Possible long runtimes/large memory usage when retrieving outlines
CVE-2026-84311 4.8 MEDIUM pypdf: Possible long runtimes/large memory usage when extracting XForm objects

IV. Related Vulnerabilities

Same product: pypdf
Same vendor: py-pdf
Same weakness: CWE-835

V. Comments for CVE-2026-84309

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