Vulnerability in plone.app.event (CVE-2026-55247)
Summary
Vulnerability in plone.app.event (CVE-2026-55247). Risk of unauthorized operations or information disclosure. Exploitable via plone.app.event. Mitigation: upgrade to 6.0.1 or later.
Original description
The description as published by the source.
Impact
By abusing the iCalendar import functionality, a logged-in editor could take the whole site offline, make the server reach into the internal network and read calendar files off disk (SSRF), and store XSS.
Patches
The problem has been patched in plone.app.event.
- For Plone 6.2: upgrade to
plone.app.event6.0.1 - For Plone 6.1: upgrade to
plone.app.event5.2.4 - For Plone 6.0: upgrade to
plone.app.event5.2.4
Workarounds
In the site root, go to the Security tab of the Zope Management Interface (manage_access), look for the "plone.app.event: Import Ical" permission, and grant this only to the Manager role. Then only users with the Manager role can use the ical import form.
There is no workaround for the stored XSS in the URL field of events.
The vulnerabilities were discovered by Timothy Dudley and responsibly reported to the Plone Security Team. Thank you!
Source: GitHub Security Advisories (Global) NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-55247 has been found in plone.app.event.
Attackers can target a specific entry point like plone.app.event over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 9.1/10.
What to do: upgrade plone.app.event to 6.0.1 or later.
If unsure, ask your IT team or search "plone.app.event CVE-2026-55247" on the vendor's site.
CVE-2026-55247 (plone.app.event) — CWE-400 / CVSS v3 9.1
Attack vector: remote (network-reachable) / no user interaction
Attack surface: plone.app.event / manage_access
Patched: 6.0.1 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-400) exists in plone.app.event. Attackers reach the vulnerable code path via plone.app.event.
Check the vendor advisory for the affected versions of plone.app.event. Attack surface: plone.app.event / manage_access.
Severity: Critical (CVSS 9.1/10). Risk of unauthorized operations or information disclosure.
Update to 6.0.1.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'plone.app.event' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'plone.app.event' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
plone.app.eventを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade plone.app.event to 6.0.1ステージング環境で 6.0.1 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。