Async JavaScript <= 2.19.07.14 - Authenticated (Subscriber+) Stored Cross-Site Scripting
Strategic Overview
- Status
- Patched in 2.20.02.27
- Affected Plugin
- Async JavaScript
- Affected Version
< 2.20.02.27- CVSS
- 6.4Medium
- Weakness type
- CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
- CVE
CVE-2020-36854
At a glance
CVE-2020-36854 is a medium-severity Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in the Async JavaScript WordPress plugin, affecting versions < 2.20.02.27. It carries a CVSS score of 6.4 (reachable over the network; low attack complexity). Exploitation requires an authenticated account at Subscriber level or above. The issue is fixed in version 2.20.02.27; sites on affected versions should update now. Disclosed February 2020, reported by Mikey Veenstra.
Vulnerability Overview
The Async JavaScript plugin for WordPress is vulnerable to Stored Cross-Site Scripting in versions up to, and including, 2.19.07.14. This is due to missing authorization checks on the aj_steps AJAX aciton along with a lack on sanitization on the settings saved via the function. This makes it possible for authenticated attackers with subscriber level permissions and above to inject malicious web scripts into a page that execute whenever a user accesses that page.
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 interaction from a victim user.
CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Reaching this weakness in Async JavaScript < 2.20.02.27 takes an account at Subscriber 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 Async JavaScript the fix is 2.20.02.27: builds < 2.20.02.27 are affected, anything from 2.20.02.27 onward is not.
Remediation
Update to version 2.20.02.27, or a newer patched version
How does WordSec protect against this?
An attacker needs Subscriber 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: Async JavaScript 2.20.02.27 closes this, and updating the plugin is the step that ends it.
- Firewall
- Alerts
External References
Related records
Same weakness class
Vulnerability data © Defiant, Inc., provided under the Wordfence Intelligence T&C