CVE-2026-10083 Overview
CVE-2026-10083 is a Stored Cross-Site Scripting (XSS) vulnerability in the APCu Manager WordPress plugin before version 4.5.0. The plugin fails to escape APCu object-cache keys before rendering them in an admin-area page. When a persistent object cache is enabled, cache keys derived from unsanitised user input are output without escaping. An unauthenticated attacker can inject JavaScript into a transient name, which then executes in the browser session of an administrator viewing the affected admin page.
Critical Impact
An unauthenticated attacker can execute arbitrary JavaScript in an administrator's browser session, enabling account takeover, plugin manipulation, and further compromise of the WordPress site.
Affected Products
- APCu Manager WordPress plugin versions prior to 4.5.0
- WordPress installations using APCu as a persistent object cache backend
- Administrator sessions viewing the APCu Manager admin page
Discovery Timeline
- 2026-06-29 - CVE-2026-10083 published to NVD
- 2026-06-29 - Last updated in NVD database
Technical Details for CVE-2026-10083
Vulnerability Analysis
The APCu Manager plugin exposes the contents of the APCu object cache in an administrative interface. Cache keys are read directly from the APCu store and rendered into the HTML response without output encoding. Because WordPress transients are stored under APCu keys when a persistent object cache is active, transient names created elsewhere on the site become attacker-controlled sinks in the admin UI.
An attacker triggers an unauthenticated request that causes the site to create a transient whose name contains HTML or JavaScript payload characters. When an administrator later opens the APCu Manager view, the malicious key is emitted verbatim into the DOM. The browser then parses the payload as script and executes it under the admin origin.
Successful exploitation yields code execution in the administrator's authenticated context. This allows the attacker to create new administrator accounts, install malicious plugins, or exfiltrate site data.
Root Cause
The root cause is missing output escaping on user-influenced data. Cache keys are treated as trusted internal identifiers, but they can originate from untrusted request parameters through transient-name propagation. The plugin does not apply esc_html() or equivalent WordPress escaping functions before rendering keys.
Attack Vector
Exploitation requires two conditions: a persistent object cache backed by APCu must be enabled, and another code path on the site must translate unsanitised input into a transient name. An unauthenticated attacker sends a crafted HTTP request that indirectly writes the payload into an APCu key. An administrator viewing the APCu Manager admin page triggers execution. User interaction from the administrator is required, which aligns with the CVSS UI:R vector component.
No verified proof-of-concept code is published. See the WPScan Vulnerability Report for technical details.
Detection Methods for CVE-2026-10083
Indicators of Compromise
- Unexpected administrator accounts, new plugins, or modified theme files following administrator visits to the APCu Manager page.
- APCu cache keys or WordPress transient names containing <script>, onerror=, onload=, or other HTML event-handler substrings.
- Outbound HTTP requests from administrator browsers to unfamiliar domains immediately after loading the APCu Manager admin view.
Detection Strategies
- Enumerate APCu keys and WordPress transients and flag any entry whose name contains HTML metacharacters such as <, >, or quote characters.
- Review web server access logs for unauthenticated requests that create or influence transient names, correlating them with subsequent admin sessions.
- Inspect the rendered HTML of the APCu Manager admin page in a controlled environment for unescaped user-controlled strings.
Monitoring Recommendations
- Alert on creation of new WordPress administrator accounts or role changes on sites running the APCu Manager plugin.
- Monitor plugin file integrity and detect modifications to core WordPress files or plugin directories.
- Log administrator page views and correlate with anomalous outbound requests originating from admin browser sessions.
How to Mitigate CVE-2026-10083
Immediate Actions Required
- Update the APCu Manager plugin to version 4.5.0 or later on all WordPress installations.
- Audit APCu keys and WordPress transients for payloads containing HTML or JavaScript characters and flush suspicious entries.
- Review WordPress administrator accounts and recent plugin or theme changes for signs of exploitation.
Patch Information
Upgrade the APCu Manager plugin to version 4.5.0 or later. The fixed release escapes cache keys before rendering them in the admin interface. Refer to the WPScan Vulnerability Report for advisory details.
Workarounds
- Deactivate the APCu Manager plugin until it can be updated to version 4.5.0 or later.
- Disable the APCu persistent object cache backend if the plugin cannot be removed immediately.
- Restrict access to the WordPress admin area with IP allowlisting or a web application firewall rule that blocks requests containing script payloads in transient-related parameters.
# Update the APCu Manager plugin using WP-CLI
wp plugin update apcu-manager --version=4.5.0
# Or deactivate the plugin as a temporary workaround
wp plugin deactivate apcu-manager
# Flush APCu cache to remove any injected keys
wp cache flush
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
