CVE-2021-38492

Mozilla: Navigating to `mk:` URL scheme could load Internet Explorer

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Severity

Moderate

Red Hat Product Security

6.1

CVSS 3.0

Review impact separately from score.

Published · September 7, 2021

Updated · November 21, 2025

Description

When delegating navigations to the operating system, Firefox would accept the mk scheme which might allow attackers to launch pages and execute scripts in Internet Explorer in unprivileged mode. This bug only affects Firefox for Windows. Other operating systems are unaffected.. This vulnerability affects Firefox < 92, Thunderbird < 91.1, Thunderbird < 78.14, Firefox ESR < 78.14, and Firefox ESR < 91.1.

CVSS score applicability

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation

No mitigation is specified in collected source.

CVSS / CWE

CVSS 3.0 · 6.1
CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

CWE-829 · Inclusion of Functionality from Untrusted Control Sphere