CVE-2023-5729 — A malicious web site can enter fullscreen mode while simultaneously triggering a

A malicious web site can enter fullscreen mode while simultaneously triggering a WebAuthn prompt. This could have obscured the fullscreen notification and could have been leveraged in a spoofing attack. This vulnerability affects Firefox < 119.

01What is this vulnerability?

A malicious web site can enter fullscreen mode while simultaneously triggering a WebAuthn prompt. This could have obscured the fullscreen notification and could have been leveraged in a spoofing attack. This vulnerability affects Firefox < 119.

02Affected products

Vendor	Product	Versions
Mozilla	Firefox	unspecified

03Active exploitation status

Not currently listed on the CISA Known Exploited Vulnerabilities (KEV) catalog. EPSS is the best forward-looking signal — see the EPSS row above.

04Recommended remediation

• Patch to a fixed version listed in the vendor advisory (see references below).
• Mitigate with WAF rules, network egress filters, or feature flags where the patch is not yet available.
• Hunt historical logs for exploitation indicators — see Detection signatures below.

05Technical details

For the full vendor write-up, exploit chains, and reference implementations, see the references list in section 09.

06Detection signatures

Ask SARA in chat to draft a starting detection for this CVE in your stack of choice.

07Related CVEs

No directly-cited follow-up CVEs in the KB record for this advisory. The references list in section 09 carries the vendor cross-references.

08Timeline

• Published: 2023-10-24T12:47:15.116Z
• Last modified: 2025-02-13T17:25:47.330Z

09References

• bugzilla.mozilla.org — https://bugzilla.mozilla.org/show_bug.cgi?id=1823720
• www.mozilla.org — https://www.mozilla.org/security/advisories/mfsa2023-45/
• security.gentoo.org — https://security.gentoo.org/glsa/202401-10