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CVE-2026-119205— pypdf: Possible infinite loop when cloning dictionaries

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 是一个免费且开源的纯 Python PDF 库。在 6.21.4 版本之前，当克隆或复制一个精心构造的循环 DictionaryObject 时，pypdf 可能会陷入无限循环。这是因为在遍历克隆对象时，代码检查的是生成的目标引用，而非原始源引用，导致某些源端循环能够绕过已访问对象的检测机制。该问题已在 6.21.4 版本中修复。

CVSS 7.1 · High

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application
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I. Basic Information for CVE-2026-119205

Vulnerability Information
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Vulnerability Title
pypdf: Possible infinite loop when cloning dictionaries
Source: CVE Program / CVE List V5
Vulnerability Description
pypdf is a free and open-source pure-python PDF library. Prior to 6.21.4, pypdf can enter an infinite loop when cloning or duplicating a crafted cyclic DictionaryObject. Clone traversal checked generated destination references rather than the original source references, allowing some source cycles to evade the visited-object check. This issue is fixed in version 6.21.4.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/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

Affected Products

Vendor Product Affected Versions CPE Subscribe
py-pdf pypdf < 6.21.4 -

II. Public POCs for CVE-2026-119205

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III. Intelligence Information for CVE-2026-119205

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Other References for CVE-2026-119205 (4)

Same Patch Batch · py-pdf · 2026-10-29 · 7 CVEs total

CVE-2026-119206 7.1 HIGH pypdf: Possible long runtimes when retrieving page labels
CVE-2026-119203 7.1 HIGH pypdf: Possible infinite loop when hitting EOF in standard xref table during trailer searc
CVE-2026-119204 7.1 HIGH pypdf: Possible large memory usage when parsing page tree
CVE-2026-119207 7.1 HIGH pypdf: Possible large memory usage for exceptions in strict mode
CVE-2026-119209 7.1 HIGH pypdf: Possible large memory usage when parsing cross-reference streams
CVE-2026-119208 7.1 HIGH pypdf: Possible long runtimes/large memory usage for encrypted PDF files

IV. Related Vulnerabilities

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