CVE-2026-109898

Executive Summary

CVE-2026-109898 is a Missing Authorization (CWE-862) vulnerability in the WordPress plugin WP Event Solution, maintained by Arraytics, affecting all versions up to and including 4.1.25. The flaw stems from incorrectly configured access control levels, allowing an unauthenticated, network-positioned attacker to invoke functionality that should be restricted to authorized users, resulting in a low-integrity impact. No public proof-of-concept, exploit code, or Nuclei template exists, and no vendor patch has been identified — the vulnerability must be treated as unpatched.

Technical Analysis

The vulnerability is classified as CWE-862 (Missing Authorization) and is described by the NVD as an "Exploiting Incorrectly Configured Access Control Security Levels" issue. In WordPress plugin terms, this class of defect occurs when a REST API route, AJAX action, or administrative handler is registered without an adequate capability check — for example, missing a current_user_can() verification or a valid permission_callback on a registered REST endpoint. As a result, the endpoint becomes reachable by unauthenticated or low-privileged callers and performs an operation that the developer intended to restrict.

The CVSS v3.1 vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N (base score 5.3, Medium) confirms the following characteristics: the attack is network-reachable (AV:N), requires no special conditions or race (AC:L), needs no authentication (PR:N) and no user interaction (UI:N), and is scoped to the vulnerable component (S:U). Confidentiality and availability are unaffected (C:N/A:N), while integrity is rated Low (I:L), meaning an attacker can modify some data but not fully compromise the system's integrity.

No specific function names, REST routes, AJAX action hooks, nonce names, database tables, or file paths are disclosed in the CNA title or NVD description provided. Therefore, the precise endpoint or parameter abused cannot be enumerated without fabricating details. What can be stated with confidence is the vulnerability class: an access-control configuration gap that exposes a privileged operation to unauthenticated callers.

The affected product is a WordPress plugin, which means the attack surface is the public web endpoint of any site running it. WordPress plugins typically expose functionality through admin-ajax.php actions, REST API namespaces, or direct PHP entry points; any of these registration paths lacking authority enforcement would be exploitable under this CVE. Because WP Event Solution handles event listings, registrations, and related content, an integrity-impacting authorization bypass most plausibly allows unauthorized creation, modification, or state changes to plugin-managed records.

EPSS is 0.00176, placing this CVE at the 6.6th percentile of exploited vulnerabilities. This is a very low exploitation-probability estimate, consistent with the absence of public exploit code and the lack of KEV listing. However, low EPSS should not be read as "not exploitable" — authorization bypasses are often weaponized opportunistically once the affected request pattern becomes known, and WordPress plugins are heavily targeted by automated scanning against large installed bases.

Exploitation Scenarios

No public PoC is available; the attack chain below is inferred from the vulnerability class (CWE-862, missing authorization) and the information explicitly provided in the NVD description. No endpoint names, parameters, or code symbols are asserted.

1. Reconnaissance / target identification. An attacker identifies internet-facing WordPress sites running WP Event Solution at version 4.1.25 or earlier. Enumeration can be performed passively via Shodan dorks targeting plugin assets in wp-content/plugins/wp-event-solution/, or actively by requesting plugin readme/asset files and version strings. Because the plugin's version is exposed through standard WordPress asset paths, precise version fingerprinting is trivial.

2. Triggering the flaw class. Missing authorization means the vulnerable handler does not verify that the caller holds the required capability. The attacker sends a crafted request directly to the affected plugin functionality over HTTP — no login, no valid session, and no user interaction are required (PR:N, UI:N). Depending on how the plugin registers the handler, this request may take the form of an unauthenticated REST call, an admin-ajax.php action, or a direct request to a plugin PHP file, but the operative mechanism is the same: the access-control check that should gate the operation is either absent or incorrectly configured, so the request is processed.

3. Payload / execution method (class level). Unlike injection flaws, an authorization bypass does not require a crafted payload to achieve its effect — the "payload" is simply a well-formed request to the under-protected endpoint carrying the parameters the operation expects. The attacker supplies legitimate-looking values for whatever state the plugin manages (for example, event records or associated settings), and the server executes the action because it never confirms the caller is authorized. No code execution, file write, or SQL injection is implied by the CVSS subscores.

4. Post-exploitation impact. Successful exploitation yields unauthorized modification of plugin-managed data — an integrity-only impact rated Low in the CVSS vector. There is no confidentiality or availability impact per the vector, so the attacker cannot read protected data or take the site down through this flaw alone. In practice, an integrity-only bypass on a WordPress plugin can still enable content tampering (e.g., unauthorized changes to event listings) and may serve as a foothold for chained abuse if the modified data is later consumed unsafely elsewhere. Full site takeover is not supported by the vector and should not be assumed.

Because no exploit artifacts exist publicly, defenders should treat the exploitation scenario as a probable but unconfirmed chain, and monitor for unauthenticated traffic to plugin-specific endpoints.

Impact Assessment

• CVSS base score: 5.3 (Medium), vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N.
• Confidentiality: None (C:N) — no protected data disclosure is indicated.
• Integrity: Low (I:L) — limited unauthorized modification of plugin-managed content or state.
• Availability: None (A:N) — no denial-of-service impact indicated.
• Attack prerequisites: None beyond network reachability. No authentication, no user interaction, no special conditions.
• Affected systems: Any WordPress installation running WP Event Solution up to and including version 4.1.25. Sites that have removed or disabled the plugin are not affected through this vector.
• Blast radius: Scoped to the vulnerable component (S:U). Impact is confined to the plugin's own data domain; it does not inherently escalate to the WordPress core or the hosting server per the CVSS assessment.
• Business impact: Integrity tampering with event data can undermine trust in published content and may violate data-integrity expectations for event registration workflows. Because exploitation is unauthenticated, an attacker can act without any credential, and because no patch exists, exposure persists until the plugin is removed or a fix is released.
• Exploit likelihood: Low per EPSS (0.00176, 6.6th percentile); no KEV listing; no public PoC, exploit code, or Nuclei template.

Detection Guidance

Sigma Rule

title: WP Event Solution Missing Authorization Attempt (CVE-2026-109898)
id: 3f9c1a72-8b64-4d21-9e5a-7c1d2f0e5b9a
status: experimental
description: Detects unauthenticated HTTP requests targeting the WP Event Solution plugin endpoint pattern associated with CVE-2026-109898.
references:
  - https://nvd.nist.gov/vuln/detail/CVE-2026-109898
author: valtersit.com
date: 2026/01/01
logsource:
  category: webserver
  product: apache
detection:
  selection_plugin:
    cs-uri-query|contains:
      - '/wp-content/plugins/wp-event-solution/'
      - 'wp-event-solution'
  selection_noauth:
    cs-method: 'POST'
  condition: selection_plugin and selection_noauth
fields:
  - c-ip
  - cs-uri
  - cs-method
falsepositives:
  - Legitimate anonymous interactions with event features
level: medium
tags:
  - attack.t1190
  - cve.2026.109898

YARA Rule

rule CVE_2026_109898_WP_Event_Solution_Missing_Auth
{
    meta:
        description = "Flags WP Event Solution plugin artifacts referenced by CVE-2026-109898 in web access/log data or plugin source paths"
        author = "valtersit.com"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-109898"
        date = "2026-01-01"
        severity = "medium"
    strings:
        $path1 = "wp-content/plugins/wp-event-solution" ascii nocase
        $path2 = "wp-event-solution" ascii nocase
        $cve   = "CVE-2026-109898" ascii
    condition:
        any of ($path*) or $cve
}

Suricata IDS Rule

alert http any any -> any any (msg:"CVE-2026-109898 WP Event Solution Missing Authorization Attempt"; flow:to_server,established; http.uri; content:"/wp-content/plugins/wp-event-solution/"; nocase; http.method; content:"POST"; classtype:attempted-user; sid:2026109898; rev:1; metadata:reference cve,CVE-2026-109898;)

Elastic Detection

sequence by source.ip with maxspan=30s
  [network where http.request.method == "POST" and
     stringContains(http.request.uri, "/wp-content/plugins/wp-event-solution/") and
     not exists(http.request.headers.authorization)]

Splunk SPL Query

index=web sourcetype=access_combined
| where match(uri, "(?i)/wp-content/plugins/wp-event-solution/")
| where method="POST"
| stats count min(_time) as first_seen max(_time) as last_seen by src_ip, uri, status
| where count > 0
| sort - count

Wazuh OSSEC Rule

<group name="web,wordpress,cve-2026-109898,">
  <rule id="2026108" level="7">
    <if_sid>31100</if_sid>
    <match>wp-content/plugins/wp-event-solution/</match>
    <description>CVE-2026-109898: Possible unauthenticated access attempt against WP Event Solution plugin endpoint</description>
    <group>cve_2026_109898,attack.t1190,</group>
  </rule>
</group>

Mitigation & Patch Guidance

Patch confidence: 0/4 (UNPATCHED — no patch evidence from any tracked source).

1. Immediate mitigations

   • If WP Event Solution is not actively required, deactivate and delete the plugin; this removes the exposed attack surface entirely.
   • If the plugin must remain active, restrict access to the plugin's endpoints at the edge using WAF rules or reverse-proxy ACLs, allowing only expected request patterns.
   • Enforce authentication at the perimeter for any plugin functionality that should never be anonymous, and audit the plugin's registration of REST/AJAX handlers for absent capability checks where possible.
   • Monitor access logs for unauthenticated POST requests to plugin paths and alert on anomalies (see Detection Guidance).

2. Patch/upgrade steps

   • No vendor fix, workaround, or patched version has been identified. Monitor the WP Event Solution changelog, the vendor site (Arraytics), and the NVD record for a fixed release.
   • If/when a patched version is published, update to the first release that contains the authorization fix, and verify the version installed is above 4.1.25.
   • Until a fix exists, treat version 4.1.25 and earlier as vulnerable on every installation.

3. Long-term hardening

   • Maintain an inventory of installed WordPress plugins and their versions, and subscribe to vulnerability feeds (NVD, WPScan) for timely notification.
   • Adopt a virtual patching capability so that newly disclosed plugin flaws can be blocked at the edge before vendor patches ship.
   • Apply least-privilege and defense-in-depth principles to WordPress deployments: restrict administrative interfaces, enforce authentication, and review plugin code for capability checks during procurement.
   • Since the root cause is a missing authorization check, prefer plugins that consistently use current_user_can() and REST permission_callback controls, and include access-control review in your plugin vetting process.

References

• NVD — CVE-2026-109898: https://nvd.nist.gov/vuln/detail/CVE-2026-109898
• CWE-862 — Missing Authorization: https://cwe.mitre.org/data/definitions/862.html
• WordPress Plugin Security / REST permission callbacks best practices: https://developer.wordpress.org/rest-api/using-the-rest-api/authentication/
• Arraytics (WP Event Solution vendor): https://wordpress.org/plugins/wp-event-solution/ (plugin distribution and changelog)
• CISA KEV Catalog (this CVE is NOT listed as of this report): https://www.cisa.gov/known-exploited-vulnerabilities-catalog

No threat-actor campaigns, exploit-in-the-wild evidence, PoC, or KEV inclusion were identified for this CVE at the time of writing.