CVE-2017-20192

Formidable Form Builder < 2.05.03 - Unauthenticated Stored Cross-Site Scripting

2017-11-13 00:00
Jouko Pynnöne

Strategic Overview

Status
Patched in 2.05.03
Affected Plugin
Formidable Forms – WordPress Form Builder for Contact Forms, Calculators, Quizzes & More
Affected Version
< 2.05.03
CVSS
8.3High
Weakness type
CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CVE
CVE-2017-20192
View all Formidable Forms – WordPress Form Builder for Contact Forms, Calculators, Quizzes & More vulnerabilities

At a glance

CVE-2017-20192 is a high-severity Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in the Formidable Forms WordPress plugin, affecting versions < 2.05.03. It carries a CVSS score of 8.3 (reachable over the network; low attack complexity). Exploitation requires no authentication. The issue is fixed in version 2.05.03; sites on affected versions should update now. Disclosed November 2017, reported by Jouko Pynnöne.

Vulnerability Overview

The Formidable Form Builder plugin for WordPress is vulnerable to Stored Cross-Site Scripting via multiple parameters submitted during form entries like 'after_html' in versions before 2.05.03 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts that execute in a victim's browser.

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 privileges on the target site, and no interaction from a victim user.

CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Formidable Forms < 2.05.03 carries this weakness at after_html, and reaching it takes no account at all. 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 Formidable Forms the fix is 2.05.03: builds < 2.05.03 are affected, anything from 2.05.03 onward is not.

Remediation

Update to version 2.05.03, or a newer patched version

How does WordSec protect against this?

Requests carrying this pattern arrive without a session, so nothing upstream of the firewall gets a chance to reject them: WordSec's web application firewall inspects request payloads before WordPress loads them. None of that substitutes for the fix: Formidable Forms 2.05.03 closes this, and updating the plugin is the step that ends it.

  • Firewall
  • Login Security
  • Alerts

External References

https://www.cve.org/CVERecord?id=CVE-2017-20192https://www.wordfence.com/threat-intel/vulnerabilities/id/900fcaab-2424-4ae8-af18-95659db0dbe3https://nvd.nist.gov/vuln/detail/CVE-2017-20192

Related records

Vulnerability data © Defiant, Inc., provided under the Wordfence Intelligence T&C