CVE-2026-11570: 
WordPress vulnerability analysis and mitigation

CVE-2026-11570 is a Stored Cross-Site Scripting (XSS) vulnerability in the User Submitted Posts WordPress plugin affecting all versions before 20260608. The flaw allows unauthenticated attackers to inject and store malicious JavaScript via the author name field when a non-default display template configuration is active. It was publicly disclosed on June 10, 2026, with the patch released on June 8, 2026 (version 20260608). The CVSS v3.1 base score is 4.2 (Medium) per NVD, though WPScan rates it 7.5 (High) (WPScan, GitHub Advisory).

The root cause is improper output escaping (CWE-79) — the plugin outputs the user-submitted author name directly into an admin-configured HTML display template without sanitization. Exploitation requires a non-default configuration where the "Name Markup" template places the %%author%% placeholder inside an HTML attribute (e.g., Submitted by: <span class="author" data-name="%%author%%">), rather than the default text-context placement. An unauthenticated attacker submits a crafted payload in the "Your Name" field (e.g., test" onmouseover="alert(document.domain)" x=") via the [user-submitted-posts] shortcode form; once an administrator publishes the post through normal editorial workflow, the payload is rendered unescaped in the attribute context for all subsequent visitors (WPScan).

Successful exploitation allows an unauthenticated attacker to persistently store malicious JavaScript that executes in the browsers of any user — including logged-in administrators — who views the affected post. This can lead to session cookie theft, credential harvesting, forged requests on behalf of authenticated users (including privilege escalation actions), or redirection to malicious sites. Confidentiality and integrity are both partially impacted; availability is not directly affected (WPScan, GitHub Advisory).

1. Reconnaissance: Identify WordPress sites using the User Submitted Posts plugin (versions before 20260608) with a page containing the [user-submitted-posts] shortcode, using tools like WPScan or manual browsing.
2. Verify non-default configuration: Confirm that under Settings > Submitted Posts > Front-end Display, the "Name Display" option is set to "Before" or "After" content, and that the "Name Markup" template places %%author%% inside an HTML attribute (e.g., Submitted by: <span data-name="%%author%%">).
3. Craft payload: Prepare an XSS payload designed to break out of the HTML attribute context, such as: test" onmouseover="alert(document.domain)" x="
4. Submit the form: As an unauthenticated visitor, navigate to the submission form page, enter the crafted payload in the "Your Name" field, fill in required Title and Content fields, and submit.
5. Wait for moderation: The submitted post enters the normal editorial workflow; once an administrator reviews and publishes it, the stored payload becomes active.
6. Trigger execution: Any visitor (including administrators) who views the published post and hovers over the author element triggers the injected JavaScript, enabling session hijacking, credential theft, or further attacks (WPScan).

• Logs: WordPress access logs showing POST requests to pages containing the [user-submitted-posts] shortcode with unusual or encoded values in the author/name parameter (e.g., quote characters, onmouseover, onerror, javascript: strings).
• Database: Stored post meta or pending submission records in the WordPress database (wp_posts, wp_postmeta) containing HTML event handler attributes (e.g., onmouseover=, onerror=, onfocus=) within author name fields.
• File System: No direct file system artifacts expected, as the payload is stored in the database.
• Browser/Client-Side: Unexpected JavaScript alerts, redirects, or outbound requests to external domains triggered when viewing posts with author name display enabled; CSP violation reports if a Content Security Policy is in place.

Update the User Submitted Posts WordPress plugin to version 20260608 or later, which escapes the author name value before rendering it in display templates (WPScan). As a temporary workaround, disable the "Name Display" option under Settings > Submitted Posts > Front-end Display, or ensure the "Name Markup" template does not place %%author%% inside an HTML attribute context. Additionally, audit previously published posts submitted via the plugin for stored XSS payloads in author name fields, and consider implementing a Content Security Policy (CSP) to limit the impact of any residual stored payloads.

The vulnerability was discovered and reported by researcher dangnosuy (affiliated with vncsglobal.vn) and verified by WPScan. No significant broader media coverage or notable community discussion beyond standard vulnerability database aggregation has been identified at this time (WPScan).