CVE-2026-3350: Image Alt Text Manager Plugin XSS Flaw

CVE-2026-3350 Overview

The Image Alt Text Manager plugin for WordPress contains a Stored Cross-Site Scripting (XSS) vulnerability affecting all versions up to and including 1.8.2. The vulnerability stems from insufficient input sanitization and output escaping when the plugin dynamically generates image alt and title attributes using a DOM parser. Authenticated attackers with Author-level access or higher can exploit this flaw to inject arbitrary web scripts into pages, which execute whenever users access the compromised content.

Critical Impact

Authenticated attackers can inject persistent malicious scripts via post titles that execute in the context of other users' browsers, potentially leading to session hijacking, credential theft, or malicious content injection across the affected WordPress site.

Affected Products

• Image Alt Text Manager plugin for WordPress versions up to and including 1.8.2
• WordPress installations utilizing vulnerable versions of the alt-manager plugin

Discovery Timeline

• 2026-03-21 - CVE CVE-2026-3350 published to NVD
• 2026-03-23 - Last updated in NVD database

Technical Details for CVE-2026-3350

Vulnerability Analysis

This Stored Cross-Site Scripting vulnerability exists in the Image Alt Text Manager plugin's handling of post titles when generating image alt and title attributes. The plugin uses a DOM parser to dynamically construct these attributes but fails to properly sanitize user-controlled input before incorporating it into the generated HTML output.

The vulnerability is classified under CWE-79 (Improper Neutralization of Input During Web Page Generation), which encompasses cross-site scripting flaws. The attack can be executed remotely over the network without user interaction, and while it requires low privileges (Author-level access), the scope is changed meaning the impact extends beyond the vulnerable component to affect other users' browsers.

The flaw allows attackers to inject scripts that persist in the database, executing whenever any user views the affected page. This makes the vulnerability particularly dangerous in multi-user WordPress environments where content is regularly viewed by administrators, editors, and visitors.

Root Cause

The root cause is insufficient input sanitization and output escaping within the alm-empty-generator.php file. Specifically, when the plugin processes post titles to generate image alt and title attributes, it fails to properly escape special HTML characters before rendering them in the page output. The vulnerable code paths can be traced to lines 150 and 295 of the affected file.

Attack Vector

The attack vector is network-based, requiring the attacker to have authenticated access to the WordPress site with at least Author-level privileges. The attacker crafts a malicious post title containing JavaScript code, which is then stored in the database. When the Image Alt Text Manager plugin processes this post and generates alt/title attributes for images, the malicious script is embedded without proper escaping. Subsequently, any user viewing a page containing the processed image will have the malicious script execute in their browser context, potentially allowing session hijacking, cookie theft, or further malicious actions.

Detection Methods for CVE-2026-3350

Indicators of Compromise

• Unexpected or suspicious JavaScript code embedded within post titles in the WordPress database
• Unusual alt or title attributes on images containing script tags, event handlers (e.g., onerror, onload), or JavaScript URI schemes
• Reports from users experiencing unexpected browser behavior or redirects when viewing pages with images
• Web application firewall (WAF) logs showing blocked XSS attempts targeting post title fields

Detection Strategies

• Implement web application firewall rules to detect and block XSS payloads in post title submissions
• Deploy content security monitoring to identify anomalous script execution patterns
• Review WordPress database for posts with suspicious title content containing HTML entities or script patterns
• Monitor browser console errors and network requests for signs of injected script execution

Monitoring Recommendations

• Enable detailed logging on WordPress authentication and content modification events
• Configure browser-based XSS protection headers (Content-Security-Policy) to limit script execution sources
• Implement real-time alerting for pattern matches on common XSS attack strings in user-submitted content
• Regularly audit plugin logs and WordPress activity logs for unusual content creation by Author-level users

How to Mitigate CVE-2026-3350

Immediate Actions Required

• Update the Image Alt Text Manager plugin to the latest patched version immediately
• Review existing posts created by Author-level users for potentially malicious titles
• Consider temporarily disabling the plugin if an immediate update is not possible
• Implement Content-Security-Policy headers to restrict inline script execution

Patch Information

A security patch has been released to address this vulnerability. The fix can be reviewed in the WordPress Plugin Changeset. Organizations should update to the latest version of the Image Alt Text Manager plugin that includes proper input sanitization and output escaping for post titles. Additional details about this vulnerability are available in the Wordfence Vulnerability Report.

Workarounds

• Restrict Author-level access to trusted users only until the plugin can be updated
• Implement a web application firewall with rules to filter XSS payloads in post submissions
• Use a security plugin to add additional input validation for post title fields
• Consider using Content Security Policy headers with strict script-src directives to mitigate script injection impact

# Add Content-Security-Policy header in Apache .htaccess
Header set Content-Security-Policy "default-src 'self'; script-src 'self'; object-src 'none';"

# Or in nginx configuration
add_header Content-Security-Policy "default-src 'self'; script-src 'self'; object-src 'none';";