The DOMParser API did not properly process '<noscript>' elements for escaping.
Priority LOW 29Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- Required
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- Low · Low · None
- Fix status
- Fixed
Attack profile from CVSS 3.1 · NVD. Fix status from CNA.
Summary
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.
Why it matters now
EPSS 0.00753 55th percentileScored 2026-11-07
Fix Fixed Firefox (Mozilla): 86
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
Remediation
- Fix · CNA Firefox (Mozilla) Fixed in 86
Fixed in the same release
Records fixed by the same vendor advisory or release, as the CNA lists them.
- Advisory ·
Mozilla Firefox — GLSA-202104-10
12 records Highest priority Priority MEDIUM 2 MEDIUM, 10 LOW
Other records, highest priority first
- TI-2021-06299 Out-of-bounds write in Mozilla FirefoxPriority MEDIUM 41
- TI-2021-06293 One phishing tactic on the web is to provide a link with HTTP Auth.Priority MEDIUM 40
- TI-2021-06297 Clickjacking in Mozilla FirefoxPriority LOW 37
Timeline
- 2026-10-02 Threatist record created from CVE-2021-23974
- 2026-10-03 Alias added: GHSA-xgvx-m8xh-737m
References
More Mozilla Firefox vulnerabilities
- TI-2024-08981 Use after free in Mozilla Firefox KEVCVSS 3.1CRITICAL 9.8
- TI-2022-09832 Use after free in Mozilla Firefox KEVCVSS 3.1CRITICAL 9.6
- TI-2019-08769 Improper input validation in Mozilla Firefox ESR KEVCVSS 3.1CRITICAL 10.0
- TI-2010-03577 Mozilla Firefox 3.5.x through 3.5.14 and 3.6.x through 3.6.11, Thunderbird 3.1.6 before… KEVCVSS 3.1CRITICAL 9.8
- TI-2023-04799 Out-of-bounds write in Google Chrome KEVCVSS 3.1HIGH 8.8
- TI-2023-04477 Out-of-bounds write in Google Chrome KEVCVSS 3.1HIGH 8.8
Sources
- CVE-2021-23974 · CVE Program
- CVE-2021-23974 · NVD
- FIRST EPSS
- GHSA-xgvx-m8xh-737m · GitHub Advisory Database · CC BY 4.0
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