Event Espresso 4 Decaf <= 4.10.11 - Cross-Site Request Forgery Bypass
Strategic Overview
- Status
- Patched in 4.10.12
- Affected Plugin
- Event Espresso – Event Registration & Ticketing Sales
- Affected Version
<= 4.10.11- CVSS
- 4.3Medium
- Weakness type
- CWE-352 · Cross-Site Request Forgery (CSRF)
- CVE
CVE-2021-4404
At a glance
CVE-2021-4404 is a medium-severity Cross-Site Request Forgery (CSRF) vulnerability in the Event Espresso WordPress plugin, affecting versions <= 4.10.11. It carries a CVSS score of 4.3 (reachable over the network; low attack complexity). Exploitation requires no authentication. The issue is fixed in version 4.10.12; sites on affected versions should update now. Disclosed August 2021, reported by Jerome Bruandet.
Vulnerability Overview
The Event Espresso 4 Decaf plugin for WordPress is vulnerable to Cross-Site Request Forgery in versions up to, and including, 4.10.11. This is due to missing or incorrect nonce validation on the ajaxHandler() function. This makes it possible for unauthenticated attackers to op into notifications 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-352: Cross-Site Request Forgery (CSRF)
Event Espresso <= 4.10.11 carries this weakness at ajaxHandler(), and reaching it takes a caller who can reach the endpoint. Cross-site request forgery abuses the fact that browsers attach a victim's cookies to any request, so a state-changing action that only checks who you are, not whether you meant to act, can be triggered from another site.
An attacker who gets a logged-in user to load a crafted page can perform that action as them, with the impact scaling to whatever the victim's role is allowed to do. For Event Espresso the fix is 4.10.12: builds <= 4.10.11 are affected, anything from 4.10.12 onward is not.
Remediation
Update to version 4.10.12, or a newer patched version
How does WordSec protect against this?
The attempt arrives as an ordinary request to Event Espresso: WordSec's web application firewall inspects request payloads before WordPress loads them. None of that substitutes for the fix: Event Espresso 4.10.12 closes this, and updating the plugin is the step that ends it.
- Firewall
- Alerts
External References
Related records
Same weakness class
Other vulnerabilities in Event Espresso – Event Registration & Ticketing Sales
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