Description
Zen is a firefox-based browser. Prior to 1.19.13b, Zen Browser did not provide a persistent, clearly visible security notification when a webpage entered fullscreen mode, allowing an attacker-controlled page to hide the real browser UI and origin information, imitate a trusted website UI, and combine with long-domain URL eliding to spoof a trusted origin for phishing and credential theft. This issue is fixed in version 1.19.13b.
References2
Metrics
- CVSS 4.0
-
6.3
MEDIUM
Score source: CNA
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - EPSS — exploit probability
- 0% percentile: 25 · as of 15 November 2026
- CWE
- CWE-451
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.