CVE-2021-29946 Explained : Impact and Mitigation

This CVE-2021-29946 article provides insights into a vulnerability that affects Firefox ESR, Thunderbird, and Firefox, allowing port blocking bypass.

Understanding CVE-2021-29946

CVE-2021-29946 involves an integer overflow vulnerability in certain ports, enabling the bypass of port blocking restrictions in affected Mozilla products.

What is CVE-2021-29946?

The vulnerability arises due to port values exceeding the bounds of a 16-bit integer, thereby evading port blocking controls when utilized in the Alt-Svc header of Firefox ESR, Thunderbird, and Firefox versions.

The Impact of CVE-2021-29946

CVE-2021-29946 creates a security loophole that potentially allows threat actors to bypass port blocking measures, compromising the security of the impacted systems.

Technical Details of CVE-2021-29946

This section delves into the specifics of the vulnerability, including its description, affected systems, and exploitation mechanism.

Vulnerability Description

The vulnerability stems from written ports causing an integer overflow beyond a 16-bit integer, thereby enabling the circumvention of port blocking protocols implemented in Firefox ESR < 78.10, Thunderbird < 78.10, and Firefox < 88.

Affected Systems and Versions

Mozilla products susceptible to this vulnerability include Firefox ESR versions less than 78.10, Thunderbird versions less than 78.10, and Firefox versions less than 88.

Exploitation Mechanism

By exploiting the integer overflow in the Alt-Svc header, threat actors could potentially bypass port blocking restrictions, gaining unauthorized access to networks or services.

Mitigation and Prevention

To address CVE-2021-29946, immediate steps, long-term security practices, and the significance of patching are discussed to enhance system security.

Immediate Steps to Take

Organizations are advised to update affected products to versions beyond the vulnerable ones as a crucial measure to mitigate the risk posed by CVE-2021-29946.

Long-Term Security Practices

Implementing robust network security measures, conducting regular vulnerability assessments, and promoting security awareness among users are recommended for long-term protection against similar vulnerabilities.

Patching and Updates

Regularly applying security patches released by Mozilla, especially those addressing CVE-2021-29946, is imperative to prevent exploitation and maintain a secure computing environment.