KLA10654
Multiple vulnerabilities in Mozilla Firefox and Firefox ESR

Multiple serious vulnerabilities have been found in Firefox. Malicious users can exploit these vulnerabilities to cause denial of service, bypass security restrictions or execute arbitrary code.

Below is a complete list of vulnerabilities

1. Use-after-free vulnerability can be exploited remotely via a specially designed web page to cause denial of service or execute arbitrary code;
2. Lack of restrictions at add-ons installation mechanism can be exploited remotely via a specially designed web page to bypass security restrictions.

Technical details

(1) can be exploited via a specially designed <canvas> element. Occurs when resize event coacts with style changes which causes recreation of original canvas reference.

Normally when user enters the URL to an add-on directly warnings are bypassed because it’s result of direct user action. data: URL could be manipulated to simulate direct user input to exploit (2). Also URL can be spoofed to manipulate user into falsely believing that installation was initiated by trusted site.

Mozilla Firefox versions earlier than 40.0.3
Mozilla Firefox ESR versions earlier than 38.2.1

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