CVE Intelligence
Critical Insecure deserialization

CVE-2026-78006 — The Events Calendar <= 6.17.4 - Unauthenticated PHP Object Injection to Remote Code Execution

The The Events Calendar plugin for WordPress is vulnerable to Remote Code Execution in all versions up to, and including, 6.17.4 via the is_safe_widget_instance function. This is due to insufficient protection in is_safe_widget_instance, which can be bypassed because PHP fires magic methods during its pre-parse, combined with enable_rendering_widget_copied() forging a valid wp_hash integrity attribute before unserialize() is reached. This makes it possible for unauthenticated attackers to execute code on the server. This is exploitable without authentication or approval because the plugin's V2 single-event template runs do_blocks() over buffered comment HTML, and WordPress returns a moderation-hash URL that allows an unauthenticated commenter to immediately view their own pending comment, delivering the injected block markup to the vulnerable code path before any moderation occurs. This does require comments to be enabled and visible on events.

Published Sep 12, 2026 · Updated Oct 15, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: Wordfence

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.
How the score was calculated
  • EPSS 1.5% (30-day exploitation probability)+11
  • Technical severity (critical)+10
  • Automatable exploitation (SSVC)+3

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation
Not confirmed
Not in CISA KEV — an absence of record, not proof it is unexploited.
EPSS FIRST
1.47%
ahead of 73% of scored CVEs · Oct 15, 2026
Affects
Stellarwp
The Events Calendar
CVSS base
9.8
Critical · 2 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation
None
none · proof-of-concept · active
Automatable
Yes
can an attacker script the kill-chain steps
Technical impact
Total
partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

  1. Identify exposed assets running the affected vendor/product/version combinations (Stellarwp The Events Calendar).
  2. The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
  3. No fix documented in the sources: reduce exposure and monitor the vendor advisory.
  4. Search available logs for exploit probes matching the vulnerability class (insecure deserialization), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Stellarwp The Events Calendar ≤ 6.17.4 Vulnerable CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactScored by
9.8 CVSS 3.1 Critical 3.9 5.9 security@wordfence.com via NIST National Vulnerability Database
9.8 CVSS 3.1 Critical — — Wordfence via CVE Program (cve.org) e CISA ADP
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H (score shown at the top: security@wordfence.com)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-502 · Deserialization of Untrusted Data

Other CVEs with this weakness →

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

  • Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
  • Monitor serialized objects in requests and unexpected processes spawned by the runtime.
web/proxy/WAF logsnetwork IDS/IPSendpoint telemetry (EDR)application logs

Timeline

What happened to this CVE, newest first.

  • 2026
  • Affected products added · stellarwp/the events calendar
    Oct 15, 2026 · CVE Program (cve.org) e CISA ADP
  • SSVC assessment updated
    Oct 15, 2026 · CVE Program (cve.org) e CISA ADP
  • Record published
    Oct 15, 2026
  • CVSS changed · 9.8
    Oct 15, 2026 · NIST National Vulnerability Database
  • Source status changed · → Deferred
    Oct 15, 2026 · NIST National Vulnerability Database
  • Record created in this database
    Oct 15, 2026 · NIST National Vulnerability Database
  • CVE published
    Sep 12, 2026 · Wordfence

Source activity

Repeated readings are counted rather than listed.

  • 1× Official description updated · Oct 15, 2026 – Oct 15, 2026

References

7 on the record

Elsewhere on this site

Stellarwp
every CVE for this vendor
Insecure deserialization
same class
CWE-502
other pages naming this weakness

Related CVEs (same products)

  • CVE-2026-78159 The Events Calendar <= 6.17.3 - Unauthenticated Code Injection to Remote Code Execution via Widget 'classes' Map Callable Invocation Sep 12, 2026
  • CVE-2026-3585 The Events Calendar <= 6.15.17 - Authenticated (Author+) Arbitrary File Read via ajax_create_import Mar 10, 2026
  • CVE-2026-2694 The Events Calendar <= 6.15.16 - Improper Authorization to Authenticated (Contributor+) Event/Organizer/Venue Update/Trash via REST API Feb 25, 2026
  • CVE-2025-15043 The Events Calendar <= 6.15.13 - Missing Authorization to Authenticated (Subscriber+) Data Migration Control Jan 20, 2026
  • CVE-2025-69352 WordPress The Events Calendar plugin <= 6.15.12.2 - Broken Access Control vulnerability Jan 6, 2026
  • CVE-2025-12192 The Events Calendar <= 6.15.9 - Sysinfo Key Incorrect Comparison to Unauthenticated Sensitive Information Exposure Nov 5, 2025

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No fixed version, patch or mitigation documented.
  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-78006 is "The Events Calendar <= 6.17.4 - Unauthenticated PHP Object Injection to Remote Code Execution", rated Critical. It affects The Events Calendar (Stellarwp); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 9.8 describes technical severity. EPSS 1.47% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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