CVE Database›Document archive›CVE-2021-23995

CVE-2021-23995

Mozilla: Use-after-free in Responsive Design Mode

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Severity

Important

Red Hat Product Security

8.8

CVSS 3.1

Review impact separately from score.

Published · April 19, 2021

Updated · November 22, 2025

Description

When Responsive Design Mode was enabled, it used references to objects that were previously freed. We presume that with enough effort this could have been exploited to run arbitrary code. This vulnerability affects Firefox ESR < 78.10, Thunderbird < 78.10, and Firefox < 88.

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 3.1 · 8.8
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

CWE-416 · Use After Free