CVE-2021-38509
4.3 · MEDIUMOverview
CVE-2021-38509 is a medium-severity vulnerability affecting mozilla firefox. It was published on December 8, 2021 and has a CVSS 3.1 base score of 4.3 (MEDIUM).
This vulnerability has a CVSS 3.1 base score of 4.3, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
Technical Description
Due to an unusual sequence of attacker-controlled events, a Javascript alert() dialog with arbitrary (although unstyled) contents could be displayed over top an uncontrolled webpage of the attacker's choosing. This vulnerability affects Firefox < 94, Thunderbird < 91.3, and Firefox ESR < 91.3.
Remediation
Check the references section for vendor advisories and patches from mozilla. Update firefox to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| mozilla | firefox | >= 0, < 94.0 | Affected |
| mozilla | firefox_esr | >= 0, < 91.3.0 | Affected |
| mozilla | thunderbird | >= 0, < 91.3.0 | Affected |
References
Frequently Asked Questions
What is CVE-2021-38509?
CVE-2021-38509 is a medium-severity vulnerability affecting mozilla firefox. It was published on December 8, 2021 and has a CVSS 3.1 base score of 4.3 (MEDIUM).
How severe is CVE-2021-38509?
This vulnerability has a CVSS 3.1 base score of 4.3, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
How do I fix or remediate CVE-2021-38509?
Check the references section for vendor advisories and patches from mozilla. Update firefox to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2021-38509?
CyberStrike's AI-powered security agents can automatically detect CVE-2021-38509 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
How CyberStrike Helps
AI agents map your attack surface to find vulnerabilities like this one.
Automated penetration testing that runs continuously, not just quarterly.
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