Yoast SEO <= 2.0.1 - Reflected Cross-Site Scripting

2015-04-20 00:00
Anonymous

Strategic Overview

Status
Patched in 2.1
Affected Plugin
Yoast SEO – Advanced SEO with real-time guidance and built-in AI
Affected Version
< 2.1
CVSS
6.1Medium
Weakness type
CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CVE
CVE pending
View all Yoast SEO – Advanced SEO with real-time guidance and built-in AI vulnerabilities

At a glance

This record tracks a medium-severity Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in the Yoast SEO WordPress plugin, affecting versions < 2.1. It carries a CVSS score of 6.1 (reachable over the network; low attack complexity). Exploitation requires no authentication. The issue is fixed in version 2.1; sites on affected versions should update now. Disclosed April 2015.

Vulnerability Overview

The Yoast SEO plugin for WordPress is vulnerable to Reflected Cross-Site Scripting in versions up to, and including, 2.0.1 due to insufficient input sanitization and output escaping on remove_query_arg and add_query_arg. This makes it possible for 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.

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

Reaching this weakness in Yoast SEO < 2.1 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 Yoast SEO the fix is 2.1: builds < 2.1 are affected, anything from 2.1 onward is not.

Remediation

Update to version 2.1, or a newer patched version

How does WordSec protect against this?

The attempt arrives as an ordinary request to Yoast SEO: WordSec's web application firewall inspects request payloads before WordPress loads them. None of that substitutes for the fix: Yoast SEO 2.1 closes this, and updating the plugin is the step that ends it.

  • Firewall
  • Alerts

External References

https://www.wordfence.com/threat-intel/vulnerabilities/id/2fe34989-493c-4883-a1ca-454262919202

Related records

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