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CVE-2026-55247— plone.app.event: Denial of service via iCalendar import

Quick assessment

Affected
plone plone.app.event
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.

为 Plone 提供事件（event）内容类型。在 5.2.4 和 6.0.1 版本之前， 中的 iCalendar 导入功能存在以下安全缺陷： 1. 对日历 URL 和事件 URL 的访问限制不足； 2. 未对下载的字节数或导入的事件数量进行充分限制； 3. 按单个事件提交事务（commit），缺乏事务保护。 因此，已登录的编辑用户（editor）可以： 使服务器请求内部网络资源或本地日历文件（可能导致服务端请求伪造 SSRF 或本地文件读取）； 耗尽服务器资源，导致站点不可用； 存储一个恶意的事件 URL，当其

CVSS 9.1 · Critical

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 2

VendorProduct Version RangeStatus
plone plone.app.event < 5.2.4 affected
>= 6.0.0, < 6.0.1 affected
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I. Basic Information for CVE-2026-55247

Vulnerability Information
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Vulnerability Title
plone.app.event: Denial of service via iCalendar import
Source: CVE Program / CVE List V5
Vulnerability Description
plone.app.event provides the event content type for Plone. Prior to versions 5.2.4 and 6.0.1, the iCalendar import in src/plone/app/event/ical/importer.py accepts insufficiently restricted calendar and event URLs, does not adequately bound downloaded bytes or imported events, and commits work per event. A logged-in editor can make the server request internal network resources or local calendar files, exhaust resources and take the site offline, and store a malicious event URL that executes script in another user's browser. The fix restricts accepted URLs, applies MAXIMUM_ICAL_IMPORT_SIZE_BYTES and MAXIMUM_ICAL_IMPORT_EVENTS limits, uses transaction savepoints, and validates event URLs. This issue is fixed in versions 5.2.4 and 6.0.1.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:H
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
plone plone.app.event < 5.2.4 -

II. Public POCs for CVE-2026-55247

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III. Intelligence Information for CVE-2026-55247

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Patches & Fixes for CVE-2026-55247 (2)

Vendor Advisories for CVE-2026-55247 (1)

Vendor Pages for CVE-2026-55247 (2)

IV. Related Vulnerabilities

Same vendor: plone
Same weakness: CWE-400

V. Comments for CVE-2026-55247

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