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CVE-2026-102998— pypdf: Possible long runtimes when generating appearance streams

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 6.19.0 版本之前，一个经过精心构造的 PDF 文件（包含表单字段值）可能导致 pypdf/generic/_appearance_stream.py 中的外观流生成逻辑在应用启用“扁平化”（flattening）选项更新字段时，在循环中重复执行不变的选择数据计算工作，从而导致运行时间过长并造成应用不可用。该问题已在 6.19.0 版本中修复。

CVSS 8.7 · High
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I. Basic Information for CVE-2026-102998

Vulnerability Information
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Vulnerability Title
pypdf: Possible long runtimes when generating appearance streams
Source: CVE Program / CVE List V5
Vulnerability Description
pypdf is a free and open-source pure-python PDF library. Prior to 6.19.0, a crafted PDF with form field values can cause pypdf/generic/_appearance_stream.py appearance-stream generation to repeat invariant selection-data work inside a loop when an application updates fields with flattening enabled, resulting in excessive runtimes and application unavailability. This issue is fixed in version 6.19.0.
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:H/SC:N/SI:N/SA:N
Source: CVE Program / CVE List V5
Vulnerability Type
未加控制的资源消耗(资源穷尽)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
py-pdf pypdf < 6.19.0 -

II. Public POCs for CVE-2026-102998

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III. Intelligence Information for CVE-2026-102998

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Other References for CVE-2026-102998 (4)

Same Patch Batch · py-pdf · 2026-09-30 · 8 CVEs total

CVE-2026-102995 8.7 HIGH pypdf: Possible large memory usage for large /ToUnicode streams (Follow-up 2)
CVE-2026-102997 8.7 HIGH pypdf: Possible long runtimes for partially malformed FlateDecode streams (Follow-up)
CVE-2026-102993 8.7 HIGH pypdf: Possible large memory usage when retrieving Roman page labels
CVE-2026-102994 8.7 HIGH pypdf: Possible long runtimes/large memory usage when parsing indirect objects
CVE-2026-102996 8.7 HIGH pypdf: Possible large memory usage when parsing font data
CVE-2026-102999 8.7 HIGH pypdf: Possible long runtimes with large amount of embedded files
CVE-2026-103000 8.7 HIGH pypdf: Possible large memory usage when retrieving alphabetical page labels

IV. Related Vulnerabilities

Same product: pypdf
Same vendor: py-pdf
Same weakness: CWE-400

V. Comments for CVE-2026-102998

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