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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.

plone.app.event是Plone组织的一个事件管理应用。 plone.app.event 5.2.4之前版本和6.0.0至6.0.1之前版本存在资源管理错误漏洞，该漏洞源于iCalendar导入功能（src/plone/app/event/ical/importer.py）对日历和事件URL限制不足，未充分限制下载字节或导入事件数量，且逐事件提交工作，可能导致已登录编辑者请求内部网络资源或本地日历文件，耗尽资源使站点离线，并存储恶意事件URL在其他用户浏览器中执行脚本。

CVSS 9.1 · Critical EPSS 0.44% · P37

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
Vulnerability Title
plone.app.event 资源管理错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
plone.app.event是Plone组织的一个事件管理应用。 plone.app.event 5.2.4之前版本和6.0.0至6.0.1之前版本存在资源管理错误漏洞，该漏洞源于iCalendar导入功能（src/plone/app/event/ical/importer.py）对日历和事件URL限制不足，未充分限制下载字节或导入事件数量，且逐事件提交工作，可能导致已登录编辑者请求内部网络资源或本地日历文件，耗尽资源使站点离线，并存储恶意事件URL在其他用户浏览器中执行脚本。
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
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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