CVE-2021-23959

MEDIUM 6.1CVE-2021-23959 · Published 26/02/2021 · updated 17/06/2026

In short

CVE-2021-23959 is a MEDIUM (CVSS 6.1) vulnerability affecting firefox (mozilla).
Chance of exploitation in the next 30 days (EPSS): 0.57%, higher than 47.2% of all vulnerabilities.
Fix: update to 85.0 or later.

Package	Affected versions	Patched versions
firefox mozilla	`< 85.0`	`85.0`

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.

References

bugzilla.mozilla.org/show_bug.cgi · Issue Tracking
mozilla.org/security/advisories/mfsa2021-03 · Release Notes

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Package

Affected versions

Patched versions

firefox

mozilla

< 85.0

85.0

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