CVE-2026-55247 json
plone.app.event: Denial of service via iCalendar import
published 2026-08-28 2 mo ago modified 2026-09-10 1 mo ago also GHSA-r82h-mqw3-fc56 , PYSEC-2026-3883 , EUVD-2026-67868
- cvss
- 9.1
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.4%
- EPSS 0.4% chance of exploitation in 30 days, percentile 38%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
- pypi plone-app-event 5.2.4, 6.0.1
CISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
- Assessed
- 2 mo ago
Exploit prediction
0.44% chance of exploitation in the next 30 days, higher than 38% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 9.1 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:H |
| OSV | 3.1 | 9.1 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:H |
| GitHub | 3.1 | 9.1 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:H |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| pypi | plone-app-event | <5.2.4 >=6.0.0a1, <6.0.1 |
5.2.4 6.0.1 |
Affected products
- plone plone.app.event
Classification
- Weakness
-
- CWE-400 Uncontrolled Resource Consumption
References
-
github.com
/plone/plone.app.event/commit/1e3c83c15a24d1a789cdb012593505bc5620e28e
web
-
github.com
/plone/plone.app.event/commit/4de5eb3ea9e4f7f1781622e6d64fc086629d1437
web
-
github.com
/plone/plone.app.event/security/advisories/GHSA-r82h-mqw3-fc56
web
-
github.com
/plone/plone.app.event/releases/tag/5.2.4
web
-
github.com
/plone/plone.app.event/releases/tag/6.0.1
web
-
github.com
/plone/plone.app.event
package
-
pypi.org
/project/plone-app-event
package
-
github.com
/advisories/GHSA-r82h-mqw3-fc56
advisory
-
nvd.nist.gov
/vuln/detail/CVE-2026-55247
advisory
Sources
- CVE List CVE-2026-55247
- GitHub Advisory GHSA-r82h-mqw3-fc56
- NVD CVE-2026-55247
- OSV PYSEC-2026-3883
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.