Privilege Escalation in Zen Browser via Context-Menu Actions

Publication date: 2026-07-09

Last updated on: 2026-07-10

Assigner: GitHub, Inc.

Description

Zen is a firefox-based browser. Prior to 1.21.5b, Zen's glance and split-view context-menu actions, Open link in glance and Split link in new tab, load a page-controlled link URL with the System principal instead of the originating page's principal, allowing a malicious web page to place a link to a file URL that can load with System privileges when opened through either context-menu item and bypass the content-to-file security check that blocks an ordinary click. This issue is fixed in version 1.21.5b.

CVSS Scores

EPSS Scores

Probability:
Percentile:

Meta Information

Published

2026-07-09

Last Modified

2026-07-10

Generated

2026-07-11

AI Q&A

2026-07-10

EPSS Evaluated

N/A

NVD

CVE-2026-57501

Affected Vendors & Products

Vendor	Product	Version / Range
zen	glance	to 1.21.5b (exc)
zen	split_view	to 1.21.5b (exc)
zen	firefox_based_browser	to 1.21.5b (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-266	A product incorrectly assigns a privilege to a particular actor, creating an unintended sphere of control for that actor.

Attack-Flow Graph

Executive Summary

This vulnerability exists in the Zen browser, which is based on Firefox. Before version 1.21.5b, certain context-menu actions called 'Open link in glance' and 'Split link in new tab' would load a link's URL with the System principal instead of the originating page's principal. This means that if a malicious web page placed a link to a file URL, opening that link through these context-menu options could load the file with System-level privileges. This bypasses the usual security check that prevents ordinary clicks from loading file URLs with elevated privileges.

Impact Analysis

The vulnerability allows a malicious web page to execute a link to a file URL with System privileges when opened via specific context-menu actions. This could potentially allow unauthorized access or execution of local files with elevated privileges, bypassing normal security restrictions.

Mitigation Strategies

To mitigate this vulnerability, you should update the Zen browser to version 1.21.5b or later, where the issue is fixed.

Hi! I’m here to help you understand CVE-2026-57501. Ask me anything about the vulnerability, its impact, or mitigation strategies.

0/70