CVE-2026-55247

CVSS 9.1 (critical) · published 2026-08-28

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.

Weakness: CWE-400

Source: NVD CVE-2026-55247

References

• https://github.com/plone/plone.app.event/commit/1e3c83c15a24d1a789cdb012593505bc5620e28e
• https://github.com/plone/plone.app.event/commit/4de5eb3ea9e4f7f1781622e6d64fc086629d1437
• https://github.com/plone/plone.app.event/releases/tag/5.2.4
• https://github.com/plone/plone.app.event/releases/tag/6.0.1
• https://github.com/plone/plone.app.event/security/advisories/GHSA-r82h-mqw3-fc56

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