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.
CVE-2026-55247
“—” beside the score: it is equal to the CVSS score beside it.
Score 9.1 from GitHub Security Advisory (severity: CRITICAL) published 2026-08-28. A secondary CVSS source baseline 9.1; sources differ by 0.0.
Also known asEUVD-2026-67868 (ENISA EUVD) · GHSA-r82h-mqw3-fc56 (GitHub Security Advisories)Source: ENISA EUVD
- High severity, but no confirmed exploitation yet
A fix is available — apply it.
- CVSS v3
- 9.1
- EG Score
- 9.1CRITICALmedium confidence
- EG Risk
- 41EG Risk 41/100
EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.
How it’s computed (value × EchelonGraph’s weight)Severity91% × 45%Impact severity (EG Severity): CVSS 9.1 of 10. Never the KEV-floored or EPSS-lifted EG Score.Exploitation0.4% × 40%FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.Automatability0% × 15%CISA's SSVC Automatable value: no (Vulnrichment).SSVC (CISA's decision table, applied by EchelonGraph): Track at every mission impact level.Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.Action: A fix is available. Apply it within your standard update timelines. - EPSS PROB
- 0.4%
- EPSS %ILE
- 38th
- KEV
- Not listed
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (9.1): severity, escalated by confirmed exploitation. This CVE's 9.1 is its impact severity (EG Severity), not escalated.
- EG Severity
- 9.1 CRITICALCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
- EG Likelihood
- 0.4% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-01). FIRST's exploitation probability, not an EchelonGraph model.
- Confirmed exploitation
- None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
- EG Priority
- SSVC Track at medium mission impactTrack at every mission impact level.CISA BOD 26-04: 60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.
SSVC (CISA's decision table, applied by EchelonGraph)Track at every mission impact level.
A fix is available. Apply it within your standard update timelines.
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table
BOD 26-04 (CISA's remediation timeline, Table 1)60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.
The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it
Published
August 28, 2026
Last Modified
September 9, 2026
Advisory Details (3)
Auto-updated Sep 15, 2026Denial of service via iCalendar import · Advisory · plone/plone.app.event · GitHub
https://github.com/plone/plone.app.event/security/advisories/GHSA-r82h-mqw3-fc56commit 4de5eb3ea9e4 (plone/plone.app.event)
Fix landed in plone/plone.app.event commit 4de5eb3ea9e4 — awaiting tagged release
https://github.com/plone/plone.app.event/commit/4de5eb3ea9e4f7f1781622e6d64fc086629d1437commit 1e3c83c15a24 (plone/plone.app.event)
Fix landed in plone/plone.app.event commit 1e3c83c15a24 — awaiting tagged release
https://github.com/plone/plone.app.event/commit/1e3c83c15a24d1a789cdb012593505bc5620e28eVendor Advisories for CVE-2026-55247(1)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
Patch Availability(2)
| Vendor / Ecosystem | Fix (by version range) / Patch | Released | Source |
|---|---|---|---|
| pip | plone.app.event @ 5.2.4 (fixes < 5.2.4) | — | ghsa |
| pip | plone.app.event @ 6.0.1 (fixes >= 6.0.0a1, < 6.0.1) | — | ghsa |
Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.
Affected Packages
(1 across 1 ecosystem)
PyPI(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| plone-app-event | 1.0 ... 6.0.0a2 (128 versions) |
| — |
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 17× in last 7d / 66× in last 30d)
Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.
Showing the most recent 100 of 133 refreshes on record for this CVE.
A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. None are among the latest 100 rows. The 33 oldest rows on record are not shown and were not checked, so the counts can still include repeats.
- 2026-11-02 02:56 UTCEG score recompute
- 2026-11-02 02:56 UTCGHSA enrichmentGHSA-r82h-mqw3-fc56 · GitHub severity CRITICAL · GitHub CVSS 9.1
- 2026-11-01 16:34 UTCEPSS rescoreEPSS 0.4% · 38th percentile
- 2026-11-01 07:44 UTCGHSA enrichmentGHSA-r82h-mqw3-fc56 · GitHub severity CRITICAL · GitHub CVSS 9.1
- 2026-11-01 07:44 UTCEG score recompute
- 2026-11-01 02:39 UTCEG score recompute
- 2026-10-31 16:33 UTCEPSS rescoreEPSS 0.4% · 38th percentile
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- 2026-10-30 16:34 UTCEPSS rescoreEPSS 0.4% · 38th percentile
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- 2026-10-28 16:32 UTCEPSS rescoreEPSS 0.4% · 38th percentile
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- 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.4% · 38th percentile
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- 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.4% · 37th percentile
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- 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.4% · 37th percentile
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- 2026-10-22 16:34 UTCEPSS rescoreEPSS 0.4% · 37th percentile
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- 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.4% · 36th percentile
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- 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.4% · 35th percentile
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- 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.4% · 35th percentile
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- 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.3% · 27th percentile
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- 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.3% · 27th percentile
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- 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.3% · 27th percentile
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- 2026-09-15 03:47 UTCEG score recompute
Related CVEs(same product + same CWE)
Same product
3 shownPyPI:plone-app-event
Frequently asked(5)
What is CVE-2026-55247?
When was the CVE record for CVE-2026-55247 published?
Is CVE-2026-55247 actively exploited?
What is the CVSS score of CVE-2026-55247?
How do I remediate CVE-2026-55247?
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-55247
Is Your Infrastructure Affected by CVE-2026-55247?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.