CVE-2025-11152: Mozilla Firefox Privilege Escalation Flaw

CVE-2025-11152 Overview

CVE-2025-11152 is a sandbox escape vulnerability caused by an integer overflow in Mozilla Firefox's Graphics: Canvas2D component. This vulnerability allows attackers to potentially break out of the browser's security sandbox by exploiting integer overflow conditions during graphics rendering operations. The flaw was addressed in Firefox version 143.0.3.

Critical Impact

This integer overflow vulnerability in the Canvas2D component enables sandbox escape, potentially allowing malicious web content to execute code outside the browser's sandboxed environment and compromise the host system.

Affected Products

• Mozilla Firefox versions prior to 143.0.3

Discovery Timeline

• 2025-09-30 - CVE-2025-11152 published to NVD
• 2026-04-13 - Last updated in NVD database

Technical Details for CVE-2025-11152

Vulnerability Analysis

This vulnerability (CWE-190: Integer Overflow or Wraparound) exists within the Graphics: Canvas2D component of Mozilla Firefox. The Canvas2D API provides functionality for drawing and manipulating 2D graphics within web pages, and this implementation contains an integer overflow condition that can be triggered through specially crafted canvas operations.

When an attacker provides malicious input that causes arithmetic calculations within the Canvas2D rendering pipeline to exceed the maximum value representable by the integer type, the value wraps around to an unexpected result. This incorrect calculation can lead to improper memory allocation sizes, buffer boundary miscalculations, or other memory safety violations that ultimately allow the attacker to escape the browser sandbox.

The network-based attack vector allows remote exploitation without requiring any privileges or user interaction, making this vulnerability particularly dangerous for users simply browsing the web.

Root Cause

The root cause is an integer overflow vulnerability (CWE-190) in the Canvas2D graphics component. The code fails to properly validate integer arithmetic operations related to canvas dimensions, pixel buffer sizes, or rendering calculations before using the results for memory operations. When these calculations overflow, the resulting incorrect values can lead to memory corruption that bypasses sandbox protections.

Attack Vector

The vulnerability can be exploited remotely over the network without authentication or user interaction. An attacker would craft a malicious web page containing JavaScript code that manipulates the Canvas2D API in a way that triggers the integer overflow condition. When a victim visits this page using a vulnerable Firefox browser, the overflow corrupts memory in a controlled manner, enabling the attacker to escape the browser sandbox and potentially execute arbitrary code on the underlying system.

The attack flow typically involves:

1. Attacker hosts malicious content on a web server or injects it via compromised advertising networks
2. Victim navigates to the malicious page using vulnerable Firefox
3. JavaScript executes Canvas2D operations that trigger the integer overflow
4. Memory corruption occurs leading to sandbox escape
5. Attacker gains code execution outside the browser sandbox

Detection Methods for CVE-2025-11152

Indicators of Compromise

• Unusual Canvas2D API calls with extremely large dimension values or pixel counts in browser logs
• Unexpected child process spawning from Firefox browser processes
• Memory access violations or crash reports originating from graphics rendering components
• Anomalous network connections initiated by Firefox renderer processes

Detection Strategies

• Monitor for Firefox crash reports related to the Canvas2D or graphics rendering subsystems
• Deploy endpoint detection rules to identify exploitation attempts targeting the Canvas2D integer overflow
• Implement web content filtering to block known malicious pages exploiting this vulnerability
• Use SentinelOne Singularity to detect post-exploitation behavior including sandbox escape attempts

Monitoring Recommendations

• Enable crash reporting and analyze Firefox crash dumps for signs of exploitation
• Monitor endpoint telemetry for unusual process creation by browser processes
• Review browser console logs for JavaScript errors related to canvas operations with abnormal values
• Implement network monitoring to detect connections to known malicious infrastructure

How to Mitigate CVE-2025-11152

Immediate Actions Required

• Update Mozilla Firefox to version 143.0.3 or later immediately
• Enable automatic updates to ensure timely deployment of security patches
• Consider temporarily using an alternative browser if immediate patching is not possible
• Review enterprise browser deployment policies to expedite critical security updates

Patch Information

Mozilla has released Firefox version 143.0.3 which addresses this vulnerability. Organizations should update all Firefox installations to this version or later as soon as possible. Detailed patch information is available in the Mozilla Security Advisory MFSA-2025-80. Additional technical details can be found in Mozilla Bug Report #1987246.

Workarounds

• Restrict access to untrusted websites through web filtering solutions
• Consider disabling JavaScript on untrusted sites using browser extensions like NoScript
• Implement network segmentation to limit potential impact of sandbox escapes
• Deploy application whitelisting to prevent unauthorized code execution even if sandbox is bypassed

# Verify Firefox version from command line
firefox --version
# Expected output should be 143.0.3 or higher for patched versions