Custom Content Shortcode <= 4.0.1 - Authenticated Stored Cross-Site Scripting
Strategic Overview
- Status
- Patched in 4.0.2
- Affected Plugin
- Custom Content Shortcode
- Affected Version
<= 4.0.1- CVSS
- 5.4Medium
- Weakness type
- CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
- CVE
CVE-2021-24826
At a glance
CVE-2021-24826 is a medium-severity Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in the Custom Content Shortcode WordPress plugin, affecting versions <= 4.0.1. It carries a CVSS score of 5.4 (reachable over the network; low attack complexity). Exploitation requires an authenticated account. The issue is fixed in version 4.0.2; sites on affected versions should update now. Disclosed February 2022, reported by Francesco Carlucci.
Vulnerability Overview
The Custom Content Shortcode WordPress plugin before 4.0.2 does not escape custom fields before outputting them, which could allow Contributor+ (v < 4.0.1) or Admin+ (v < 4.0.2) users to perform Cross-Site Scripting attacks even when the unfiltered_html is disallowed. Please note that such attack is still possible by admin+ in single site blogs by default (but won't be when the unfiltered_html is disallowed)
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 Custom Content Shortcode <= 4.0.1 takes any authenticated account. 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 Custom Content Shortcode the fix is 4.0.2: builds <= 4.0.1 are affected, anything from 4.0.2 onward is not.
Remediation
Update to version 4.0.2, or a newer patched version
How does WordSec protect against this?
The attempt arrives as an ordinary request to Custom Content Shortcode: WordSec's web application firewall inspects request payloads before WordPress loads them. None of that substitutes for the fix: Custom Content Shortcode 4.0.2 closes this, and updating the plugin is the step that ends it.
- Firewall
- Alerts
External References
Related records
Same weakness class
Other vulnerabilities in Custom Content Shortcode
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