Back to Database
Status published
Medium
CVE-2021-23959
An XSS bug in internal error pages could have led...
Vulnerability Description
An XSS bug in internal error pages could have led to various spoofing attacks, including other error pages and the address bar. Note: This issue only affected Firefox for Android. Other operating systems are unaffected. This vulnerability affects Firefox < 85.
Impact Analysis
Refer to official advisory for detailed impact metrics.
Remediation
Ensure systems are updated to the latest vendor-supplied patch levels.
THREAT MONITOR
Am I Vulnerable?
Launch our assessment wizard to check if your infrastructure is exposed to • CVE-2021-23959
Credits & Attribution
No credits recorded in the NVD database.
References
More from Mozilla
View All →CVE-2025-9187
Memory safety bugs fixed in Firefox 142 and Thunderbird 142
Unknown
0
CVE-2025-9186
Spoofing issue in the Address Bar component of Firefox Focus for Android
Unknown
0
CVE-2025-9185
Memory safety bugs fixed in Firefox ESR 115.27, Firefox ESR 128.14, Thunderbird ESR 128.14, Firefox ESR 140.2, Thunderbird ESR 140.2, Firefox 142 and Thunderbird 142
Unknown
0
CVE-2025-9184
Memory safety bugs fixed in Firefox ESR 140.2, Thunderbird ESR 140.2, Firefox 142 and Thunderbird 142
Unknown
0
CVE-2025-9183
Spoofing issue in the Address Bar component
Unknown
0
Affected Vendor
Mozilla
View all reports →Affected Software
Firefox
Vulnerable Versions:
< 85
Timeline
Official Publish:
February 26th, 2021
Last Modified:
August 3rd, 2024
Added to House:
July 21st, 2026
CVSS Vectors
V3:
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Weaknesses (CWE)
No CWE data available
MITRE ATT&CK TTPs
No associated TTPs found for this vulnerability.