CVE-2026-4267
Published: 31 March 2026
Summary
CVE-2026-4267 is a high-severity Cross-site Scripting (CWE-79) vulnerability in Wordpress (inferred from references). Its CVSS base score is 7.2 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 13.4th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified are NIST 800-53 SI-10 (Information Input Validation) and SI-15 (Information Output Filtering).
Deeper analysis
CVE-2026-4267 is a reflected cross-site scripting (XSS) vulnerability in the Query Monitor plugin for WordPress, affecting all versions up to and including 3.20.3. The flaw stems from insufficient input sanitization and output escaping of the $_SERVER['REQUEST_URI'] parameter, as exposed in files like output/html/request.php at lines 60 and 70. It has a CVSS v3.1 base score of 7.2 (AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N) and is associated with CWE-79 (Cross-Site Scripting). The vulnerability was published on 2026-03-31.
Unauthenticated attackers can exploit this vulnerability remotely with low complexity and no privileges required. By crafting malicious payloads in the REQUEST_URI parameter, they can inject arbitrary web scripts into pages. According to the CVSS vector, no user interaction is needed despite the description noting scenarios like tricking users into clicking links; successful exploitation allows limited confidentiality and integrity impacts with changed scope.
Advisories from CleanTalk Research and Wordfence Threat Intelligence provide details on the issue, while the Query Monitor plugin's changeset 3486705 indicates a patch addressing the sanitization flaws. Security practitioners should update to a version beyond 3.20.3 via the WordPress plugin repository to mitigate the risk.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-17397
Vulnerability details
The Query Monitor – The developer tools panel for WordPress plugin for WordPress is vulnerable to Reflected Cross-Site Scripting via the ‘$_SERVER['REQUEST_URI']’ parameter in all versions up to, and including, 3.20.3 due to insufficient input sanitization and output escaping. This…
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makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that execute if they can successfully trick a user into performing an action such as clicking on a link.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Reflected XSS in public-facing WordPress plugin directly enables exploitation of public-facing applications (T1190) via crafted REQUEST_URI and facilitates arbitrary JavaScript execution in the browser (T1059.007).
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Directly addresses the insufficient input sanitization of the $_SERVER['REQUEST_URI'] parameter to prevent reflected XSS payload injection.
Enforces output filtering and escaping for REQUEST_URI-derived content to block execution of injected arbitrary web scripts.
Requires identification, reporting, and correction of the specific flaw in Query Monitor versions up to 3.20.3 via patching as indicated in changeset 3486705.