CVE-2021-43543 : Security Advisory and Response

This CVE affects Thunderbird, Firefox ESR, and Firefox by allowing documents to escape CSP sandbox restrictions when embedding content.

Understanding CVE-2021-43543

This vulnerability impacts multiple Mozilla products due to a sandbox directive bypass.

What is CVE-2021-43543?

Documents loaded with the CSP sandbox directive could evade script restrictions within the sandbox by incorporating extra content.

The Impact of CVE-2021-43543

Affected products: Thunderbird < 91.4.0, Firefox ESR < 91.4.0, and Firefox < 95
This vulnerability could potentially lead to security breaches and unauthorized script execution.

Technical Details of CVE-2021-43543

The technical details of this CVE provide insights into the vulnerability and its exploitation.

Vulnerability Description

The issue allows for the bypass of the CSP sandbox directive when embedding, compromising script restrictions.

Affected Systems and Versions

Thunderbird < 91.4.0
Firefox ESR < 91.4.0
Firefox < 95

Exploitation Mechanism

Attackers can exploit this vulnerability by loading documents that manipulate the CSP sandbox directive, thus overriding script restrictions.

Mitigation and Prevention

Mitigation strategies and steps to safeguard systems against this vulnerability.

Immediate Steps to Take

Update Thunderbird, Firefox ESR, and Firefox to versions 91.4.0 and 95 respectively.
Implement content security policies (CSP) to restrict content types and sources.

Long-Term Security Practices

Regularly review and update security configurations and policies.
Conduct security audits to identify and address potential vulnerabilities.

Patching and Updates

Apply security patches provided by Mozilla promptly.