{"id":"CVE-2026-55247","state":"PUBLISHED","title":"plone.app.event: Denial of service via iCalendar import","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.","publishedAt":"2026-08-28T18:59:01.212Z","updatedAt":"2026-08-31T18:48:31.264Z","severity":{"score":9.1,"label":"Critical","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:H","source":"GitHub_M"},"assigner":"GitHub_M","products":["plone plone.app.event"],"affected":[{"vendor":"plone","product":"plone.app.event","versions":[{"version":"< 5.2.4","status":"affected"},{"version":">= 6.0.0, < 6.0.1","status":"affected"}]}],"references":["https://github.com/plone/plone.app.event/security/advisories/GHSA-r82h-mqw3-fc56","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"],"weaknesses":["CWE-400"],"ingestedAt":"2026-10-29T20:12:24.861Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/55xxx/CVE-2026-55247.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-55247","state":"PUBLISHED","datePublished":"2026-08-28T18:59:01.212Z","dateUpdated":"2026-08-31T18:48:31.264Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-06-16T16:44:00.624Z"},"containers":{"cna":{"title":"plone.app.event: Denial of service via iCalendar import","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"plone","product":"plone.app.event","versions":[{"version":"< 5.2.4","status":"affected"},{"version":">= 6.0.0, < 6.0.1","status":"affected"}]}],"references":[{"url":"https://github.com/plone/plone.app.event/security/advisories/GHSA-r82h-mqw3-fc56","name":"https://github.com/plone/plone.app.event/security/advisories/GHSA-r82h-mqw3-fc56","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/plone/plone.app.event/commit/1e3c83c15a24d1a789cdb012593505bc5620e28e","name":"https://github.com/plone/plone.app.event/commit/1e3c83c15a24d1a789cdb012593505bc5620e28e","tags":["x_refsource_MISC"]},{"url":"https://github.com/plone/plone.app.event/commit/4de5eb3ea9e4f7f1781622e6d64fc086629d1437","name":"https://github.com/plone/plone.app.event/commit/4de5eb3ea9e4f7f1781622e6d64fc086629d1437","tags":["x_refsource_MISC"]},{"url":"https://github.com/plone/plone.app.event/releases/tag/5.2.4","name":"https://github.com/plone/plone.app.event/releases/tag/5.2.4","tags":["x_refsource_MISC"]},{"url":"https://github.com/plone/plone.app.event/releases/tag/6.0.1","name":"https://github.com/plone/plone.app.event/releases/tag/6.0.1","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"HIGH","baseScore":9.1,"baseSeverity":"CRITICAL","confidentialityImpact":"LOW","integrityImpact":"LOW","privilegesRequired":"LOW","scope":"CHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:H","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-400","lang":"en","description":"CWE-400: Uncontrolled Resource Consumption","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-08-28T18:59:01.212Z"},"source":{"advisory":"GHSA-r82h-mqw3-fc56","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-08-31T18:48:16.302616Z","id":"CVE-2026-55247","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-08-31T18:48:31.264Z"}}]}}}