CVE-2015-4513

What it actually does

Unspecified memory corruption flaws in the browser rendering engine allow remote attackers to trigger crashes or execute arbitrary code by supplying crafted web content.

Why it matters to the business

Users running outdated Firefox releases face risk of browser crashes that disrupt work and potential full compromise of the workstation leading to data theft or malware installation.

How an attack unfolds

An attacker hosts or compromises a web page containing specially crafted content that the vulnerable browser engine processes; the malformed data corrupts memory structures, allowing the attacker to control execution flow and run arbitrary code on the victim's system.

How to fix it

Upgrade Firefox to version 42.0 or later, or ESR 38.4 or later. On Debian 11/12/13 apply package version 3.16.2-1 or newer. On Ubuntu 14.04 LTS apply kernel package 3.13.0-119.166 or equivalent listed fixed versions for each flavor; on Ubuntu 16.04 LTS apply the corresponding fixed packages such as 4.2.0-16.19 or 4.4.0-1001.10.

How to confirm the fix worked

Verify installed Firefox version is 42.0 or ESR 38.4 or newer; confirm Linux package versions match or exceed the listed fixed releases for each distribution and flavor.

Typical attack path

1. Host or compromise a web server delivering malicious HTML/JavaScript
2. Victim visits the page with an affected Firefox version
3. Browser engine processes the unknown vector and corrupts memory
4. Attacker gains code execution or causes denial of service

How to detect it

Review Firefox crash reports and application logs for unexpected memory faults around the time of suspected incidents; correlate with web proxy logs showing visits to unknown or suspicious domains.

What your security team should do

• Immediately update all Firefox instances to the fixed releases listed for each platform
• Disable automatic loading of untrusted web content where possible until patches are deployed
• Monitor for any remaining outdated Firefox deployments via asset inventory
• Review browser crash logs for signs of memory corruption after patching