{"cve":"CVE-2026-55247","nvd":{"published":"2026-08-28T20:18:26.890","modified":"2026-09-09T21:09:13.080","status":"Deferred","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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:H","score":9.1},"cwes":["CWE-400"],"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"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:50:50.842544443+00:00"},"epss":{"cve":"CVE-2026-55247","score":0.00441,"percentile":0.38318,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-r82h-mqw3-fc56","url":"https://osv.dev/vulnerability/GHSA-r82h-mqw3-fc56","summary":"plone.app.event vulnerable to denial of service via iCalendar import","modified":"2026-09-10T12:25:52.689617832Z","packages":[{"ecosystem":"PyPI","name":"plone-app-event","purl":"pkg:pypi/plone-app-event","ranges":["<5.2.4"],"fixed":["5.2.4"]},{"ecosystem":"PyPI","name":"plone-app-event","purl":"pkg:pypi/plone-app-event","ranges":[">=6.0.0a1 <6.0.1"],"fixed":["6.0.1"]}]},{"id":"PYSEC-2026-3883","url":"https://osv.dev/vulnerability/PYSEC-2026-3883","summary":"plone.app.event vulnerable to denial of service via iCalendar import","modified":"2026-09-10T12:15:10.120206929Z","packages":[{"ecosystem":"PyPI","name":"plone-app-event","purl":"pkg:pypi/plone-app-event","ranges":["<5.2.4",">=6.0.0a1 <6.0.1"],"fixed":["5.2.4","6.0.1"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}