CVE-2026-25438
Published: 19 March 2026
Summary
CVE-2026-25438 is a high-severity Cross-site Scripting (CWE-79) vulnerability. Its CVSS base score is 7.1 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Drive-by Compromise (T1189); ranked at the 11.8th 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).
Threat & Defense at a Glance
Threat & Defense Details
Mitigating Controls (NIST 800-53 r5)AI
Directly addresses reflected XSS by filtering and encoding information outputs during web page generation to neutralize malicious scripts.
Prevents exploitation of the vulnerability by validating and sanitizing untrusted user inputs before they are reflected in web pages.
Mitigates the specific flaw in the Gutenberg Blocks plugin by identifying, patching, and deploying fixes to remediate the improper input neutralization.
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Reflected XSS in public-facing WordPress plugin directly enables malicious link delivery leading to browser JS execution (T1189 Drive-by Compromise via crafted URLs on vulnerable site; T1059.007 JavaScript for arbitrary script execution in victim context).
NVD Description
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in ThemeHunk Gutenberg Blocks unlimited-blocks allows Reflected XSS.This issue affects Gutenberg Blocks: from n/a through <= 1.2.8.
Deeper analysisAI
CVE-2026-25438 is an Improper Neutralization of Input During Web Page Generation vulnerability, classified as Reflected Cross-site Scripting (XSS) under CWE-79, in the ThemeHunk Gutenberg Blocks unlimited-blocks WordPress plugin. This issue affects the plugin from unknown initial versions (n/a) through version 1.2.8.
The vulnerability carries a CVSS v3.1 base score of 7.1 (AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:L), indicating network accessibility, low attack complexity, no required privileges, user interaction needed, and changed scope with low impacts to confidentiality, integrity, and availability. An unauthenticated attacker can exploit it by crafting malicious input that reflects unsanitized on a vulnerable site, tricking users (e.g., site visitors or admins) into interacting via a malicious link or form submission, thereby executing scripts in the victim's browser context.
The Patchstack advisory (https://patchstack.com/database/Wordpress/Plugin/unlimited-blocks/vulnerability/wordpress-gutenberg-blocks-unlimited-blocks-for-gutenberg-plugin-1-2-8-reflected-cross-site-scripting-xss-vulnerability?_s_id=cve) documents the Reflected XSS in Gutenberg Blocks unlimited-blocks for the Gutenberg plugin at version 1.2.8, providing details for practitioners to assess and address exposure in WordPress environments.
Details
- CWE(s)