Microsoft Clarity <= 0.3 - Authenticated Stored Cross-Site Scripting
Strategic Overview
- Status
- Patched in 0.4
- Affected Plugin
- Microsoft Clarity
- Affected Version
<= 0.3- CVSS
- 5.4Medium
- Weakness type
- CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
- CVE
CVE-2021-33850
At a glance
CVE-2021-33850 is a medium-severity Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in the Microsoft Clarity WordPress plugin, affecting versions <= 0.3. 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 0.4; sites on affected versions should update now. Disclosed October 2021, reported by Cyber Security Works Pvt. Ltd.
Vulnerability Overview
There is a Cross-Site Scripting vulnerability in Microsoft Clarity version 0.3. The XSS payload executes whenever the user changes the clarity configuration in Microsoft Clarity version 0.3. The payload is stored on the configuring project Id 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.
CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Reaching this weakness in Microsoft Clarity <= 0.3 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 Microsoft Clarity the fix is 0.4: builds <= 0.3 are affected, anything from 0.4 onward is not.
Remediation
Update to version 0.4, or a newer patched version
How does WordSec protect against this?
The attempt arrives as an ordinary request to Microsoft Clarity: WordSec's web application firewall inspects request payloads before WordPress loads them. None of that substitutes for the fix: Microsoft Clarity 0.4 closes this, and updating the plugin is the step that ends it.
- Firewall
- Alerts
External References
Related records
Other vulnerabilities in Microsoft Clarity
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