Form Builder <= 1.9.8.3 - Authenticated Stored Cross-Site Scripting
Strategic Overview
- Status
- Patched in 1.9.8.4
- Affected Plugin
- Form Builder | Create Responsive Contact Forms
- Affected Version
<= 1.9.8.3- CVSS
- 5.5Medium
- Weakness type
- CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
- CVE
CVE-2021-24513
At a glance
CVE-2021-24513 is a medium-severity Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in the Form Builder WordPress plugin, affecting versions <= 1.9.8.3. It carries a CVSS score of 5.5 (reachable over the network; low attack complexity). Exploitation requires an authenticated account. The issue is fixed in version 1.9.8.4; sites on affected versions should update now. Disclosed August 2021, reported by Felipe Restrepo Rodriguez (pfelilpe).
Vulnerability Overview
The Form Builder | Create Responsive Contact Forms WordPress plugin before 1.9.8.4 does not sanitise or escape its Form Title, allowing high privilege users such as admin to set Cross-Site Scripting payload in them, even when the unfiltered_html capability is disallowed
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 Form Builder <= 1.9.8.3 takes any authenticated account. 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 Form Builder the fix is 1.9.8.4: builds <= 1.9.8.3 are affected, anything from 1.9.8.4 onward is not.
Remediation
Update to version 1.9.8.4, or a newer patched version
How does WordSec protect against this?
The attempt arrives as an ordinary request to Form Builder: WordSec's web application firewall inspects request payloads before WordPress loads them. None of that substitutes for the fix: Form Builder 1.9.8.4 closes this, and updating the plugin is the step that ends it.
- Firewall
- Alerts
External References
Related records
Same weakness class
Other vulnerabilities in Form Builder | Create Responsive Contact Forms
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