CVE-2019-11763 : Security Advisory and Response

A flaw in the handling of null bytes during the processing of HTML entities by Firefox, Thunderbird, and Firefox ESR versions before specific releases could lead to cross-site scripting (XSS) vulnerabilities.

Understanding CVE-2019-11763

This CVE describes a vulnerability in the HTML parsing mechanism of Mozilla products, potentially enabling XSS attacks.

What is CVE-2019-11763?

The vulnerability arises from incorrect handling of null bytes in HTML entities, allowing HTML comment text to be mistaken as HTML, potentially leading to XSS attacks under specific conditions.

The Impact of CVE-2019-11763

The vulnerability could allow malicious actors to execute XSS attacks by concealing HTML entities from filters, posing a risk to the security of web applications.

Technical Details of CVE-2019-11763

This section provides detailed technical insights into the CVE-2019-11763 vulnerability.

Vulnerability Description

The flaw in HTML entity processing could result in HTML comment text being treated as HTML, potentially leading to XSS attacks.

Affected Systems and Versions

Firefox versions before 70
Thunderbird versions before 68.2
Firefox ESR versions before 68.2

Exploitation Mechanism

The vulnerability could be exploited by crafting HTML entities to bypass filters and execute XSS attacks.

Mitigation and Prevention

Protecting systems from CVE-2019-11763 requires immediate actions and long-term security practices.

Immediate Steps to Take

Update affected Mozilla products to versions 70 (Firefox), 68.2 (Thunderbird), and 68.2 (Firefox ESR) or newer.
Implement web application firewalls to detect and prevent XSS attacks.

Long-Term Security Practices

Regularly monitor and update web application security measures.
Educate developers on secure coding practices to prevent XSS vulnerabilities.

Patching and Updates

Apply security patches provided by Mozilla promptly to address the vulnerability and enhance system security.