CVE-2026-18021 Overview
CVE-2026-18021 affects the Beaver Builder Page Builder – Drag and Drop Website Builder plugin for WordPress. The vulnerability allows unauthenticated attackers to execute arbitrary shortcodes on affected sites. The flaw exists in all plugin versions up to and including 2.10.3.1. It stems from an action that fails to validate a value before passing it to the WordPress do_shortcode function. The issue is classified as [CWE-94] Improper Control of Generation of Code.
Critical Impact
Unauthenticated network attackers can trigger arbitrary WordPress shortcodes, which may expose site content, invoke plugin functionality, or interact with other shortcode-driven components on the target site.
Affected Products
- Beaver Builder Page Builder – Drag and Drop Website Builder (Lite version) for WordPress
- All versions up to and including 2.10.3.1
- Fixed in version 2.10.3.2
Discovery Timeline
- 2026-09-08 - CVE-2026-18021 published to NVD
- 2026-09-08 - Last updated in NVD database
Technical Details for CVE-2026-18021
Vulnerability Analysis
Beaver Builder exposes a WordPress action handler that accepts a user-controlled value and forwards it to do_shortcode without adequate validation. Because the handler does not require authentication, remote users can reach the vulnerable code path over the network. When the handler invokes do_shortcode, WordPress parses and executes any registered shortcode contained in the supplied string. Attackers can enumerate shortcodes provided by the theme and other installed plugins, then invoke them outside of their intended context. The impact depends on which shortcodes are registered on the target site, but the vulnerability provides a primitive for arbitrary shortcode execution.
Root Cause
The root cause is missing input validation on a value passed to do_shortcode inside the Beaver Builder plugin. The vulnerable code path lives in classes/class-fl-builder.php, referenced in the WordPress Beaver Builder Code Review. The handler treats attacker-controlled input as trusted shortcode syntax, matching the [CWE-94] improper control of code generation pattern.
Attack Vector
Exploitation requires only network access to the WordPress site. No authentication, user interaction, or elevated privileges are required. An attacker submits a crafted request that reaches the vulnerable action handler and supplies a shortcode string as the untrusted value. WordPress then expands the shortcode server-side. Depending on the shortcodes registered on the target, an attacker may retrieve restricted content, trigger arbitrary plugin actions, or chain shortcode outputs into further attacks. See the Wordfence Vulnerability Report for additional context.
Detection Methods for CVE-2026-18021
Indicators of Compromise
- Unauthenticated POST or GET requests to WordPress admin-ajax.php referencing Beaver Builder actions with shortcode content in parameter values.
- Web server logs showing repeated requests containing square-bracket shortcode syntax (for example [shortcode_name ...]) from a single client.
- Unexpected shortcode output rendered in HTTP responses to unauthenticated clients.
Detection Strategies
- Inspect WordPress access logs for requests targeting Beaver Builder AJAX endpoints with request bodies containing shortcode markers.
- Enable WordPress plugin auditing to flag versions of beaver-builder-lite-version at or below 2.10.3.1.
- Alert on outbound HTTP activity from the web host that correlates with shortcode-triggered actions, such as SSRF-capable shortcodes issuing external requests.
Monitoring Recommendations
- Monitor plugin inventory across managed WordPress sites and flag installations that have not been updated to 2.10.3.2 or later.
- Track anomalous spikes in requests to Beaver Builder AJAX handlers, particularly from unauthenticated sessions.
- Ingest WordPress and reverse-proxy logs into a centralized analytics platform to correlate shortcode-execution attempts across multiple sites.
How to Mitigate CVE-2026-18021
Immediate Actions Required
- Update the Beaver Builder plugin to version 2.10.3.2 or later on every affected WordPress site.
- Audit installed plugins and themes for shortcodes that expose sensitive functionality and constrain their use.
- Review web server and WordPress logs for prior exploitation attempts targeting Beaver Builder AJAX endpoints.
Patch Information
The vendor addressed the vulnerability in Beaver Builder 2.10.3.2. The fix is documented in the Beaver Builder Change Log Entry, which shows the validation added ahead of the do_shortcode call. Site administrators should apply the update through the WordPress plugin manager or WP-CLI.
Workarounds
- If patching is delayed, deactivate the Beaver Builder plugin until the update can be installed.
- Restrict access to wp-admin/admin-ajax.php at the web application firewall layer for known Beaver Builder actions until the plugin is updated.
- Remove or disable third-party shortcodes that expose sensitive data or actions to limit the blast radius of any shortcode execution primitive.
# Update Beaver Builder using WP-CLI
wp plugin update beaver-builder-lite-version --version=2.10.3.2
wp plugin list --name=beaver-builder-lite-version --fields=name,status,version
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
