# CVE-2026-45150: Zen Browser UI misrepresentation in fullscreen mode

Source: https://junglewise.ai/threats/cve-2026-45150-zen-browser-ui-misrepresentation-in-fullscreen-mode  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-15. Updated: 2026-07-15  
License: CC BY 4.0 with a link back

CVE-2026-45150 · Severity: info · CVSS 6.3 · Published 2026-07-15

Zen Browser, a web browser based on Firefox, failed to provide adequate security warnings when a website entered fullscreen mode. This allowed malicious websites to hide the browser's address bar and interface, making it possible to perfectly imitate legitimate websites like banks or email providers. An attacker could use this to trick users into entering sensitive credentials or personal information on a fraudulent page.

Technologies: [Zen Browser](https://junglewise.ai/threats/technologies/zen-browser). Vendors: [Zen Browser](https://junglewise.ai/threats/vendors/zen-browser).

## Quick answers

**Is CVE-2026-45150 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-45150 being exploited in the wild.

**How severe is CVE-2026-45150?** Informational severity, with a CVSS score of 6.3, published 15 July 2026.

**Which products and versions are affected?** Zen Browser < 1.19.13b.

**Is there a fix for CVE-2026-45150?** A patch was published on 2026-07-15: Fix confirmed in version 1.19.13b Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-45150 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-45150?** Check whether you run Zen Browser at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A UI misrepresentation vulnerability (CWE-451) existed in Zen Browser prior to version 1.19.13b due to the lack of a persistent, non-spoofable security indicator when the Fullscreen API is invoked. By entering fullscreen mode, a malicious site could hide the browser's chrome, including the address bar and origin information. When combined with long-domain URL eliding, an attacker can effectively spoof a trusted origin to conduct credential theft or session hijacking. The vulnerability requires user interaction (e.g., clicking an element) to trigger the fullscreen state. The issue is resolved in version 1.19.13b by ensuring origin visibility is maintained or clearly signaled.

## Affected products

- Zen Browser Zen Browser < 1.19.13b

## Timeline

- 2026-05-13: advisory: GitHub advisory published by developer
- 2026-07-15: disclosed: CVE published to NVD dataset
- 2026-07-15: patched: Fix confirmed in version 1.19.13b

## References

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

## Related threats

- [Zen Browser Privilege Escalation in Glance and Split-View Context Menus](https://junglewise.ai/threats/cve-2026-57501-zen-browser-privilege-escalation-in-glance-and-split-view-context)
- [Zen Browser address bar spoofing via long subdomains](https://junglewise.ai/threats/cve-2026-44659-zen-browser-address-bar-spoofing-via-long-subdomains)
- [Zen Browser Improper Input Validation in RSS Live-Folders](https://junglewise.ai/threats/cve-2026-44658-zen-browser-improper-input-validation-in-rss-live-folders)
- [Zen Browser improper signature verification in MAR updater](https://junglewise.ai/threats/cve-2026-41431-zen-browser-improper-signature-verification-in-mar-updater)