CVE-2026-103065

Executive Summary

CVE-2026-103065 is a high-severity vulnerability in the Themeum Kirki WordPress plugin (versions up to and including 6.3.1), classified as CWE-1284: Improper Validation of Specified Quantity in Input. The flaw allows unauthenticated remote attackers to access functionality that is not properly constrained by Access Control Lists (ACLs), resulting in unauthorized data exposure and partial integrity impact. With a CVSS score of 8.2 and no vendor patch available, organizations running the affected plugin are exposed to exploitation until a fix is released.

Technical Analysis

The vulnerability resides in the Themeum Kirki plugin, a widely used WordPress toolkit that provides customizer framework functionality. The core issue is CWE-1284, which describes a failure to validate the quantity or size of an input parameter. This class of flaw typically occurs when an application accepts a numeric or count-based input (such as an array index, a loop counter, a limit, or an offset) without enforcing boundaries or sanity checks. In the context of the Kirki plugin, the vulnerable component processes a user-supplied quantity value that lacks proper validation, allowing the attacker to reach code paths or data that should be protected by ACLs.

Because the CVSS vector indicates PR:N (no privileges required) and AV:N (network accessible), the vulnerable endpoint is reachable without authentication. The attack surface is therefore any WordPress installation with the Kirki plugin enabled and accessible over HTTP/HTTPS. The "Accessing Functionality Not Properly Constrained by ACLs" wording from the NVD description indicates that the improper validation enables a bypass of access control checks — likely by manipulating the quantity parameter to influence which resources or operations the plugin exposes. The confidentiality impact is rated High (C:H), meaning sensitive data could be read; integrity impact is Low (I:L), suggesting limited ability to modify data; availability impact is None (A:N).

No public proof-of-concept, Nuclei template, or exploit code is available at the time of writing. The technical mechanism is inferred from the vulnerability class and the NVD description only; no specific function names, file paths, or parameter names are provided in the source data. The affected version range is from "n/a" (earliest) through 6.3.1. The patch confidence is rated 0/4 — UNPATCHED — with no patch evidence from any tracked source, meaning no official fix or workaround is currently available from the vendor.

Exploitation Scenarios

Given the absence of public exploit code and specific implementation details, the following attack chain is described at the vulnerability-class level based strictly on the NVD description and CWE-1284.

1. Reconnaissance / Target Identification: An attacker scans for WordPress sites and fingerprints the presence of the Kirki plugin by requesting known plugin assets or checking HTML source for Kirki-related paths. Shodan or similar search engines can identify exposed installations using the dorks provided in the metadata.

2. Triggering the Flaw: The attacker sends a crafted HTTP request to a plugin endpoint that accepts a quantity-related input parameter. Because the plugin fails to validate the specified quantity (CWE-1284), the input is processed without proper bounds or type checking. This manipulation causes the application to evaluate an access control decision incorrectly — for example, by using the unvalidated quantity to determine which internal function or data set to expose, thereby bypassing ACLs.

3. Payload / Execution: The attacker does not need authentication. The payload is a direct request containing the malformed quantity value. The exact parameter name and endpoint are not disclosed in the available data and must not be fabricated. At the class level, the attack exploits improper input validation to reach functionality that should require elevated privileges.

4. Post-Exploitation Impact: Successful exploitation allows the attacker to access functionality and data not properly constrained by ACLs. This can lead to unauthorized disclosure of sensitive information (Confidentiality: High), and limited ability to alter data (Integrity: Low). No denial of service is expected (Availability: None). The attacker may leverage the exposed functionality to further enumerate the WordPress environment or pivot to other components.

No public PoC is available; the attack chain is inferred from the vulnerability class and CVSS vector.

Impact Assessment

The business impact is significant for any organization running WordPress with the Kirki plugin version 6.3.1 or earlier. The CVSS score of 8.2 (High) reflects a network-exploitable, unauthenticated flaw with high confidentiality impact and low integrity impact. The blast radius includes all sites where the plugin is installed and reachable. Because Kirki is a popular customizer framework, it may be bundled with themes or other plugins, increasing the potential install base. Sensitive data — such as configuration details, user information, or internal API responses — could be exposed. The lack of a patch (0/4 confidence) means defenders cannot rely on vendor remediation and must apply compensating controls. The EPSS score is not yet available, so exploit likelihood cannot be quantified from that metric. CISA KEV does not list this CVE, indicating no confirmed active exploitation in the wild at this time.

Detection Guidance

Sigma Rule

title: Kirki Plugin CWE-1284 ACL Bypass Attempt
id: 8f4a2c1e-9b3d-4a7f-8c2e-1d5f6a7b8c9d
status: experimental
description: Detects HTTP requests targeting the Kirki WordPress plugin with suspicious quantity parameters that may indicate CWE-1284 exploitation.
author: Threat Intelligence
date: 2026-01-01
logsource:
    category: webserver
    product: apache
    service: http
detection:
    selection:
        cs-method: 'GET'
        cs-uri-stem|contains:
            - '/wp-content/plugins/kirki'
            - '/wp-json/kirki'
    suspicious_param:
        cs-uri-query|contains:
            - 'quantity='
            - 'count='
            - 'limit='
            - 'offset='
            - 'num='
    condition: selection and suspicious_param
fields:
    - c-ip
    - cs-uri-stem
    - cs-uri-query
    - cs-user-agent
falsepositives:
    - Legitimate plugin usage with unusual but valid parameters
level: high
tags:
    - attack.t1190
    - cve.2026.103065

YARA Rule

rule CVE_2026_103065_Kirki_CWE1284
{
    meta:
        description = "Detects exploitation attempts against Themeum Kirki plugin CVE-2026-103065"
        author = "Threat Intelligence"
        date = "2026-01-01"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-103065"
        severity = "high"

    strings:
        $kirki_path = "/wp-content/plugins/kirki" ascii wide nocase
        $kirki_rest = "/wp-json/kirki" ascii wide nocase
        $quantity = "quantity=" ascii wide nocase
        $count = "count=" ascii wide nocase
        $limit = "limit=" ascii wide nocase
        $invalid_qty = /quantity=[^0-9&]/ ascii wide

    condition:
        (any of ($kirki_path, $kirki_rest)) and
        (any of ($quantity, $count, $limit, $invalid_qty))
}

Suricata IDS Rule

alert http any any -> any any (msg:"CVE-2026-103065 Themeum Kirki CWE-1284 ACL Bypass Attempt"; flow:established,to_server; http.uri; content:"/wp-content/plugins/kirki"; http.uri; content:"quantity="; http.uri; pcre:"/quantity=[^0-9]/i"; classtype:attempted-admin; sid:2026103065; rev:1; reference:cve,2026-103065; metadata:created_at 2026_01_01, updated_at 2026_01_01;)

Elastic Detection

sequence by source.ip with maxspan=5s
  [network where network.protocol == "http" and
   url.path : "/wp-content/plugins/kirki*" and
   url.query : "*quantity=*"]
  [network where network.protocol == "http" and
   url.path : "/wp-content/plugins/kirki*" and
   url.query : "*count=*" or url.query : "*limit=*"]

Splunk SPL Query

index=web sourcetype=access_combined
| search uri_path="/wp-content/plugins/kirki*" OR uri_path="/wp-json/kirki*"
| rex field=uri_query "(?i)(?<param>quantity|count|limit|offset|num)=[^0-9&]"
| where isnotnull(param)
| stats count by src_ip, uri_path, uri_query, http_user_agent
| sort - count

Wazuh OSSEC Rule

<group name="web,appsec,">
  <rule id="100065" level="12">
    <if_sid>31100</if_sid>
    <url>/wp-content/plugins/kirki</url>
    <regex>quantity=[^0-9]</regex>
    <description>CVE-2026-103065: Kirki plugin CWE-1284 ACL bypass attempt detected</description>
    <mitre>
      <id>T1190</id>
    </mitre>
    <group>cve_2026_103065,</group>
  </rule>
</group>

Mitigation & Patch Guidance

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

1. Immediate Mitigations: Disable or deactivate the Kirki plugin if it is not essential to site operation. If the plugin must remain active, restrict access to the vulnerable endpoints using a Web Application Firewall (WAF) to block requests with malformed quantity parameters. Enforce strict input validation at the edge by rejecting any parameter value that does not match a whitelist of expected numeric formats. Apply network-level controls to limit access to the WordPress admin and plugin endpoints to trusted IP ranges only.

2. Patch/Upgrade Steps: No official patch is available from the vendor at this time. Monitor the Themeum Kirki plugin page and WordPress plugin repository for a security release. Once a patched version is published, upgrade immediately to the latest version beyond 6.3.1. Subscribe to vendor security advisories and CVE feeds for updates.

3. Long-Term Hardening: Implement a vulnerability management program that tracks WordPress plugins and themes, with automated alerts for known CVEs. Enforce the principle of least privilege for all plugin functionality. Conduct regular security audits of third-party plugins, including code reviews for input validation and ACL enforcement. Deploy a WAF with virtual patching capabilities to mitigate unpatched vulnerabilities. Maintain an inventory of all installed plugins and their versions to rapidly identify exposure when new CVEs are published.

References

• NVD Entry: https://nvd.nist.gov/vuln/detail/CVE-2026-103065
• CWE-1284: Improper Validation of Specified Quantity in Input — https://cwe.mitre.org/data/definitions/1284.html
• MITRE ATT&CK T1190: Exploit Public-Facing Application — https://attack.mitre.org/techniques/T1190/
• WordPress Plugin Directory: Themeum Kirki — https://wordpress.org/plugins/kirki/
• EPSS: Not yet scored by FIRST.org — https://api.first.org/data/v1/epss?cve=CVE-2026-103065

No known threat actor campaigns or exploit-in-the-wild evidence is available for CVE-2026-103065 at this time. CISA KEV does not list this vulnerability.