CVE-2023-4053: Full screen notification obscured by external program

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.8% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2023-08-01 · updated 2026-06-17
Weakness: CWE-59

Description

A website could have obscured the full screen notification by using a URL with a scheme handled by an external program, such as a mailto URL. This could have led to user confusion and possible spoofing attacks. This vulnerability affects Firefox < 116, Firefox ESR < 115.2, and Thunderbird < 115.2.

Affected products

Mozilla Firefox: before 116.0 — fixed in 116.0

How to fix

Upgrade to a fixed version: Mozilla Firefox 116.0. Check the vendor advisory for mitigations.

References

https://bugzilla.mozilla.org/show_bug.cgi?id=1839079
https://www.mozilla.org/security/advisories/mfsa2023-29/
https://www.mozilla.org/security/advisories/mfsa2023-36/
https://www.mozilla.org/security/advisories/mfsa2023-38/
https://bugzilla.mozilla.org/show_bug.cgi?id=1839079
https://www.mozilla.org/security/advisories/mfsa2023-29/
https://www.mozilla.org/security/advisories/mfsa2023-36/
https://www.mozilla.org/security/advisories/mfsa2023-38/

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