CVE-2021-43543

Mozilla: Bypass of CSP sandbox directive when embedding

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Severity

Moderate

Red Hat Product Security

6.1

CVSS 3.0

Review impact separately from score.

Published · December 7, 2021

Updated · November 22, 2025

Description

Documents loaded with the CSP sandbox directive could have escaped the sandbox's script restriction by embedding additional content. This vulnerability affects Thunderbird < 91.4.0, Firefox ESR < 91.4.0, and Firefox < 95.

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-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')