What is the CVSS score of CVE-2026-2121?

CVE-2026-2121 has a CVSS 3.1 base score of 4.4 (Medium). CVSS vector: CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:L/I:L/A:N. EPSS exploitation probability: 0.0%.

Which versions of WordPress are affected by CVE-2026-2121?

Organizations using all should be aware of moderate risk from CVE-2026-2121, a cross-site scripting vulnerability rated CVSS 4.4.

How to fix or mitigate CVE-2026-2121?

Within 30 days: Identify affected systems running all and apply vendor patches as part of regular patch cycle. Verify Content-Security-Policy and output encoding.

WordPress CVE-2026-2121

EUVD-2026-14151 MEDIUM

Cross-site Scripting (XSS) (CWE-79)

2026-03-21 Wordfence

GHSA-qf9c-wfj4-w8fw

WordPress XSS

4.4

CVSS 3.1 · NVD

Severity by source

NVD PRIMARY

4.4 MEDIUM

AV:N/AC:H/PR:H/UI:N/S:C/C:L/I:L/A:N

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:L/I:L/A:N

Attack Vector

Network

Attack Complexity

High

Privileges Required

High

User Interaction

None

Scope

Changed

Confidentiality

Low

Integrity

Low

Availability

None

Lifecycle Timeline

EUVD ID Assigned

Mar 21, 2026 - 04:00 euvd

EUVD-2026-14151

Analysis Generated

Mar 21, 2026 - 04:00 vuln.today

CVE Published

Mar 21, 2026 - 03:27 nvd

MEDIUM 4.4

DescriptionCVE.org

The Weaver Show Posts plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'add_class' parameter in all versions up to, and including, 1.8.1. This is due to insufficient input sanitization and output escaping on user supplied attributes. This makes it possible for authenticated attackers, with Administrator-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. This primarily affects multisite installations where Administrators do not have the unfiltered_html capability.

AnalysisAI

The Weaver Show Posts plugin for WordPress contains a Stored Cross-Site Scripting (XSS) vulnerability in the 'add_class' parameter due to insufficient input sanitization and output escaping. Authenticated attackers with Administrator-level access can inject arbitrary web scripts that execute when users access injected pages, with particular impact in multisite installations where Administrators lack the unfiltered_html capability. A proof-of-concept demonstration exists, though the CVSS 4.4 score reflects the high privilege requirement needed for exploitation.

Technical ContextAI

This vulnerability is an instance of CWE-79 (Improper Neutralization of Input During Web Page Generation), affecting the Weaver Show Posts plugin (CPE: cpe:2.3:a:wpweaver:weaver_show_posts:*:*:*:*:*:*:*:*) across all versions up to and including 1.8.1. The flaw resides in the posts-widgets.php file (lines 32 and 45 as referenced in the plugin repository) where the 'add_class' parameter is processed without proper sanitization before being rendered in HTML output. WordPress plugins typically execute PHP code server-side and output HTML to browsers; in this case, the plugin fails to escape user-supplied class attribute values, allowing attackers to break out of the attribute context and inject script tags or event handlers. The vulnerability manifests as Stored XSS because the malicious payload is persisted in the WordPress database (likely in widget settings or post metadata) and executed every time the affected page is rendered.

RemediationAI

Update the Weaver Show Posts plugin to a version released after 1.8.1 that includes input sanitization and output escaping fixes for the 'add_class' parameter; check the official WordPress plugin repository or vendor advisory (https://www.wordfence.com/threat-intel/vulnerabilities/id/e0d525ab-a86d-4750-9d16-731cbc0a626e) for the patched version number. Until a patch is available or applied, restrict Administrator-level access to trusted personnel only, conduct an audit of existing Show Posts widgets to identify any suspicious or unfamiliar class attributes in the plugin settings, and consider disabling the plugin if it is not actively used. In multisite installations, ensure that the unfiltered_html capability remains restricted and implement WordPress security hardening practices such as two-factor authentication for Administrator accounts and regular security scanning.