What’s Vulnerable › Vulnerabilities

CVE-2021-23958

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.9% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-02-26 · updated 2026-06-17
• Weakness: CWE-668

Description

The browser could have been confused into transferring a screen sharing state into another tab, which would leak unintended information. This vulnerability affects Firefox < 85.

Affected products

• Mozilla Firefox: before 85.0 — fixed in 85.0

How to fix

Upgrade to a fixed version: Mozilla Firefox 85.0. Check the vendor advisory for mitigations.

References

• https://bugzilla.mozilla.org/show_bug.cgi?id=1642747
• https://www.mozilla.org/security/advisories/mfsa2021-03/
• https://bugzilla.mozilla.org/show_bug.cgi?id=1642747
• https://www.mozilla.org/security/advisories/mfsa2021-03/

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