WPBakery Page Builder Clipboard <= 4.5.5 - Stored Cross-Site Scripting
Strategic Overview
- Status
- Patched in 4.5.6
- Affected Plugin
- WPBakery Page Builder Clipboard
- Affected Version
< 4.5.6- CVSS
- 6.4Medium
- Weakness type
- CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
- CVE
CVE-2021-24243
At a glance
CVE-2021-24243 is a medium-severity Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in the WPBakery Page Builder Clipboard WordPress plugin, affecting versions < 4.5.6. It carries a CVSS score of 6.4 (reachable over the network; low attack complexity). The issue is fixed in version 4.5.6; sites on affected versions should update now. Disclosed April 2021, reported by Charles Strader Sweethill.
Vulnerability Overview
An AJAX action registered by the WPBakery Page Builder (Visual Composer) Clipboard WordPress plugin before 4.5.6 did not have capability checks nor sanitization, allowing low privilege users (subscriber+) to call it and set XSS payloads, which will be triggered in all backend pages.
Technical Analysis
The vector marks this flaw as remotely reachable over the network, with low attack complexity — no special timing or configuration is needed, and no interaction from a victim user.
CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Reaching this weakness in WPBakery Page Builder Clipboard < 4.5.6 takes a caller who can reach the endpoint. Cross-site scripting happens when input from a request is written into a page without being escaped for the context it lands in, so the browser parses attacker-supplied text as markup or script.
Injected script runs with the privileges of whoever views the affected page, which is how these flaws turn into administrator session theft, silent account creation or persistent backdoors in page content. For WPBakery Page Builder Clipboard the fix is 4.5.6: builds < 4.5.6 are affected, anything from 4.5.6 onward is not.
Remediation
Update to version 4.5.6, or a newer patched version
How does WordSec protect against this?
The attempt arrives as an ordinary request to WPBakery Page Builder Clipboard: WordSec's web application firewall inspects request payloads before WordPress loads them. None of that substitutes for the fix: WPBakery Page Builder Clipboard 4.5.6 closes this, and updating the plugin is the step that ends it.
- Firewall
- Alerts
External References
Related records
Other vulnerabilities in WPBakery Page Builder Clipboard
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