CVE-2017-7783 : Security Advisory and Response

A denial of service vulnerability in Firefox versions older than 55 can be triggered by using a lengthy username in a site URL.

Understanding CVE-2017-7783

This CVE involves a security flaw in Firefox that can lead to a denial of service when a specific URL format is used.

What is CVE-2017-7783?

When a long username is included in a username/password combination within a site URL, it can cause the modal prompt to become unresponsive or crash, resulting in a denial of service. This vulnerability affects Firefox versions prior to 55.

The Impact of CVE-2017-7783

The vulnerability can be exploited to trigger a denial of service attack, potentially disrupting the availability of the affected Firefox browser.

Technical Details of CVE-2017-7783

This section provides more technical insights into the vulnerability.

Vulnerability Description

The vulnerability arises when a lengthy username is used in a specific URL format, causing the modal prompt to hang or crash, leading to a denial of service.

Affected Systems and Versions

Product: Firefox
Vendor: Mozilla
Versions Affected: Older than 55

Exploitation Mechanism

Exploiting this vulnerability involves crafting a URL with a long username and password combination to trigger the unresponsive or crashing modal prompt.

Mitigation and Prevention

Protecting systems from CVE-2017-7783 requires specific actions to mitigate the risk.

Immediate Steps to Take

Update Firefox to a version equal to or newer than 55 to prevent exploitation of this vulnerability.
Avoid using excessively long usernames in URLs to reduce the risk of triggering the denial of service.

Long-Term Security Practices

Regularly update browsers and software to the latest versions to patch known vulnerabilities.
Educate users on safe browsing practices to minimize the risk of falling victim to similar exploits.
Implement network security measures to detect and prevent potential denial of service attacks.

Patching and Updates

Ensure timely installation of security patches and updates provided by Mozilla to address CVE-2017-7783 and other known vulnerabilities.