CVE-2021-24427

W3 Total Cache <= 2.1.2 Authenticated (Admin+) Stored Cross-Site Scripting

2021-06-16 00:00
R3N0

Strategic Overview

Status
Patched in 2.1.3
Affected Plugin
W3 Total Cache
Affected Version
< 2.1.3
CVSS
4.8Medium
Weakness type
CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CVE
CVE-2021-24427
View all W3 Total Cache vulnerabilities

At a glance

CVE-2021-24427 is a medium-severity Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in the W3 Total Cache WordPress plugin, affecting versions < 2.1.3. It carries a CVSS score of 4.8 (reachable over the network; low attack complexity). Exploitation requires an authenticated account at Admin level or above. The issue is fixed in version 2.1.3; sites on affected versions should update now. Disclosed June 2021, reported by R3N0.

Vulnerability Overview

The W3 Total Cache plugin for WordPress is vulnerable to Stored Cross-Site Scripting via several CDN settings in versions up to, and including, 2.1.2 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers with administrative level permissions and above to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. This only affects multi-site installations and installations where unfiltered_html has been disabled.

Technical Analysis

The vector marks this flaw as remotely reachable over the network, with low attack complexity — no special timing or configuration is needed.

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

Reaching this weakness in W3 Total Cache < 2.1.3 takes an account at Admin level or above. 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 W3 Total Cache the fix is 2.1.3: builds < 2.1.3 are affected, anything from 2.1.3 onward is not.

Remediation

Update to version 2.1.3, or a newer patched version

How does WordSec protect against this?

An attacker needs Admin access first, so the firewall sees the attempt as traffic from a logged-in account: WordSec's web application firewall inspects request payloads before WordPress loads them. None of that substitutes for the fix: W3 Total Cache 2.1.3 closes this, and updating the plugin is the step that ends it.

  • Firewall
  • Alerts

External References

https://www.cve.org/CVERecord?id=CVE-2021-24427https://www.wordfence.com/threat-intel/vulnerabilities/id/9d9cf724-9ae7-4414-88d1-10640491df34https://nvd.nist.gov/vuln/detail/CVE-2021-24427

Related records

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