Critical Vulnerability in Mozilla Firefox

Number: AV15-071
Date: 07 August 2015


The purpose of this advisory is to raise awareness of critical vulnerabilities in Mozilla Firefox and FireFox ESR for which upgrades are now available.


A critical vulnerability has been reported in Mozilla Firefox and FireFox ESR which could be exploited by an attacker with a specially crafted web page to read and steal sensitive local files on the victim's computer. Mozilla is reporting it has received reports that an exploit based on this vulnerability has been found in the wild.

Mozilla Foundation Security Advisory Numbers: 2015-78

CVE References: CVE-2015-4495

Affected Versions:

Suggested Action

Upgrade to Firefox 39.0.3 or Firefox ESR 38.1.1

CCIRC recommends that systems administrators identify affected products in their environment and follow their patch management process accordingly.


Note to Readers

In support of Public Safety's mission to build a safe and resilient Canada, CCIRC's mandate is to help ensure the security and resilience of the vital non-federal government cyber systems that underpin Canada's national security, public safety and economic prosperity. As Canada's computer security incident response team, CCIRC is Canada's national coordination centre for the prevention and mitigation of, preparedness for, response to, and recovery from cyber incidents on non-federal government systems. It does this by providing authoritative advice and support, and coordinating information sharing and incident response.

Please note, CCIRC PGP key has recently been updated.

For general information, please contact Public Safety Canada's Public Affairs division at:

Telephone: 613-944-4875 or 1-800-830-3118
Fax: 613-998-9589

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