MC4WP: Mailchimp for WordPress <= 4.8.4 - Open Redirect

2021-06-01 00:00
WPScanTeam

Strategic Overview

Status
Patched in 4.8.5
Affected Plugin
MC4WP: Mailchimp for WordPress
Affected Version
<= 4.8.4
CVSS
6.1Medium
Weakness type
CWE-601 · URL Redirection to Untrusted Site ('Open Redirect')
CVE
CVE pending
View all MC4WP: Mailchimp for WordPress vulnerabilities

At a glance

This record tracks a medium-severity URL Redirection to Untrusted Site ('Open Redirect') vulnerability in the MC4WP WordPress plugin, affecting versions <= 4.8.4. 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 4.8.5; sites on affected versions should update now. Disclosed June 2021, reported by WPScanTeam.

Vulnerability Overview

The MC4WP: Mailchimp for WordPress for WordPress is vulnerable to Open Redirection via the '_redirect_to ' parameter in versions up to, and including, 4.8.4. This makes it possible for unauthenticated attackers to arbitrarily redirect administrators via a forged request granted they can trick a site administrator into performing an action such as clicking on a link.

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-601: URL Redirection to Untrusted Site ('Open Redirect')

MC4WP <= 4.8.4 carries this weakness at _redirect_to, and reaching it takes a caller who can reach the endpoint. An open redirect is a page that takes a destination from the request and sends the browser there without checking that the destination belongs to the site.

A link that starts on a trusted domain finishes on an attacker's, which is what makes phishing and consent-screen abuse credible to the person clicking it. For MC4WP the fix is 4.8.5: builds <= 4.8.4 are affected, anything from 4.8.5 onward is not.

Remediation

Update to version 4.8.5, or a newer patched version

How does WordSec protect against this?

The attempt arrives as an ordinary request to MC4WP: WordSec's web application firewall inspects request payloads before WordPress loads them. None of that substitutes for the fix: MC4WP 4.8.5 closes this, and updating the plugin is the step that ends it.

  • Firewall
  • Alerts

External References

https://www.wordfence.com/threat-intel/vulnerabilities/id/dd7db465-ebeb-477b-b6c8-a9b89ba2372b

Related records

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