CVE-2021-23998

6.5 mediumEPSS 0.6%

Medium (6.5) in mozilla. EPSS 0.6% chance of exploitation in the next 30 days.

Through complicated navigations with new windows, an HTTP page could have inherited a secure lock icon from an HTTPS page. This vulnerability affects Firefox ESR < 78.10, Thunderbird < 78.10, and Firefox < 88.

Severity

CVSS 3.1

6.5 medium

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N

EPSS: 0.6% chance of exploitation in the next 30 days; higher than 48% of CVEs (scores of 2026-10-31)
CWE: CWE-345
Published: 2021-06-24
Modified: 2026-06-17
Record from: the NVD, synced 2026-10-19

Affected

mozilla:firefox
mozilla:firefox_esr
mozilla:thunderbird

References

https://bugzilla.mozilla.org/show_bug.cgi?id=1667456
https://www.mozilla.org/security/advisories/mfsa2021-14/
https://www.mozilla.org/security/advisories/mfsa2021-15/
https://www.mozilla.org/security/advisories/mfsa2021-16/
https://bugzilla.mozilla.org/show_bug.cgi?id=1667456

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