CVE-2021-23974
MEDIUMCVSS 6.1/10EPSS 0.75%
Last modified
CVE-2021-23974 is a medium-severity vulnerability rated 6.1/10 on the CVSS scale. The DOMParser API did not properly process '<noscript>' elements for escaping. This could be used as an mXSS vector to bypass an HTML Sanitizer. EPSS estimates a 0.75% chance of exploitation in the next 30 days.
Description
The DOMParser API did not properly process '<noscript>' elements for escaping. This could be used as an mXSS vector to bypass an HTML Sanitizer. This vulnerability affects Firefox < 86.
Metrics
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Mozilla | Firefox | < 86.0 |
References
- https://bugzilla.mozilla.org/buglist.cgi?bug_id=1528997%2C1683627Issue Tracking, Vendor Advisory
- https://security.gentoo.org/glsa/202104-10Third Party Advisory
- https://www.mozilla.org/security/advisories/mfsa2021-07/Release Notes, Vendor Advisory
- https://bugzilla.mozilla.org/buglist.cgi?bug_id=1528997%2C1683627Issue Tracking, Vendor Advisory
- https://security.gentoo.org/glsa/202104-10Third Party Advisory
- https://www.mozilla.org/security/advisories/mfsa2021-07/Release Notes, Vendor Advisory
Timeline
- Published
- Last Modified
- Status
- Modified
Frequently Asked Questions
What is CVE-2021-23974?
The DOMParser API did not properly process '<noscript>' elements for escaping. This could be used as an mXSS vector to bypass an HTML Sanitizer. This vulnerability affects Firefox < 86.
How severe is CVE-2021-23974?
CVE-2021-23974 has a CVSS score of 6.1/10 (MEDIUM severity). The EPSS model estimates a 0.75% probability of exploitation in the next 30 days.
How do I fix CVE-2021-23974?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.
How Strix Helps
- How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
- Autonomous PentestingAI agents that find and validate exploitable vulnerabilities like this one across your applications.
- PR ReviewsPentest every pull request so vulnerable code is caught before it ships to production.
- AI Penetration TestingHow AI-driven penetration testing continuously covers your attack surface.
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Are you affected by CVE-2021-23974?
Run a free Strix scan to check your systems for this vulnerability.
Scan your code nowSource: NVD / NIST