CVE-2026-7322: Mozilla Firefox RCE Vulnerability

CVE-2026-7322 Overview

CVE-2026-7322 is a memory safety vulnerability affecting multiple versions of Mozilla Firefox and Firefox ESR. Memory safety bugs were identified in Firefox ESR 115.35.0, Firefox ESR 140.10.0, and Firefox 150.0.0. Some of these bugs showed evidence of memory corruption, and Mozilla presumes that with enough effort, some of these could have been exploited to run arbitrary code. This vulnerability is classified under CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer).

Critical Impact

Multiple memory corruption bugs could potentially be chained together to achieve arbitrary code execution in affected Firefox browser versions, putting user systems at risk of compromise.

Affected Products

• Firefox 150.0.0
• Firefox ESR 140.10.0
• Firefox ESR 115.35.0

Discovery Timeline

• April 28, 2026 - CVE-2026-7322 published to NVD
• April 28, 2026 - Last updated in NVD database

Technical Details for CVE-2026-7322

Vulnerability Analysis

This vulnerability encompasses multiple memory safety bugs affecting Firefox's core browser engine. Memory safety issues represent a broad category of vulnerabilities where the software fails to properly manage memory operations, potentially leading to memory corruption conditions. The affected Firefox versions contain bugs that showed evidence of memory corruption during testing or analysis by Mozilla's security team.

The vulnerability is accessible via the network without requiring user interaction or special privileges, making it particularly concerning for browser security. An attacker who successfully exploits these memory safety issues could potentially achieve arbitrary code execution within the context of the browser process. This could allow the attacker to install malware, steal sensitive information, or pivot to attack other systems on the network.

Multiple bug IDs are associated with this vulnerability, as tracked in Mozilla's Bugzilla, indicating this is a collection of related memory safety issues rather than a single isolated bug.

Root Cause

The root cause is classified as CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer. This occurs when the software performs operations on a memory buffer but fails to properly restrict those operations to the intended buffer boundaries. In the context of Firefox, this can manifest in various components of the browser engine where memory is dynamically allocated and manipulated during web content rendering, JavaScript execution, or media processing.

Attack Vector

The attack vector is network-based, meaning an attacker could potentially exploit this vulnerability by crafting malicious web content that triggers the memory corruption when processed by the browser. This could be delivered through:

• Malicious websites visited by the user
• Malicious advertisements served on legitimate websites
• Embedded content in emails or documents that open in the browser
• Compromised legitimate websites serving exploit code

The vulnerability can be exploited without any authentication or special privileges, and without requiring user interaction beyond visiting a malicious page.

The memory corruption manifests within Firefox's browser engine components during content processing. Due to the nature of memory safety bugs, exploitation typically involves carefully crafting input that triggers an out-of-bounds memory access, use-after-free condition, or similar memory corruption primitive. For detailed technical information, refer to Mozilla Security Advisory MFSA-2026-35.

Detection Methods for CVE-2026-7322

Indicators of Compromise

• Unexpected Firefox crashes or instability, particularly when visiting unfamiliar websites
• Unusual child processes spawned by the Firefox browser process
• Suspicious network connections originating from Firefox to unknown external hosts
• Memory access violations or exception logs in system event logs related to Firefox

Detection Strategies

• Monitor for unusual memory allocation patterns or crashes in Firefox processes using endpoint detection tools
• Implement browser isolation solutions to contain potential exploitation attempts
• Deploy SentinelOne agents configured to detect anomalous browser behavior and memory corruption exploitation techniques
• Review browser crash reports for patterns indicating exploitation attempts

Monitoring Recommendations

• Enable enhanced logging for browser processes to capture crash dumps and memory access violations
• Monitor network traffic for connections to known malicious infrastructure following browser activity
• Implement behavioral analysis to detect post-exploitation activities such as code execution or data exfiltration
• Track Firefox version deployments across the enterprise to identify unpatched systems

How to Mitigate CVE-2026-7322

Immediate Actions Required

• Update Firefox to version 150.0.1 immediately
• Update Firefox ESR to version 140.10.1 or 115.35.1 depending on your deployment channel
• Enable automatic updates for Firefox to ensure timely patching of future vulnerabilities
• Consider temporarily restricting browser access to untrusted websites until patching is complete

Patch Information

Mozilla has released patched versions that address these memory safety bugs:

• Firefox: Update to version 150.0.1
• Firefox ESR 140.x: Update to version 140.10.1
• Firefox ESR 115.x: Update to version 115.35.1

For detailed patch information, refer to the official Mozilla Security Advisories:

• MFSA-2026-35
• MFSA-2026-36
• MFSA-2026-37

Workarounds

• Deploy browser isolation technology to contain potential exploitation in a sandboxed environment
• Implement content filtering to block access to untrusted or potentially malicious websites
• Consider using an alternative browser temporarily until Firefox can be updated
• Enable Firefox's enhanced tracking protection and strict security settings to reduce attack surface

# Configuration example
# Verify Firefox version on Linux/macOS
firefox --version

# Force Firefox update check via command line
# Navigate to Help > About Firefox in the browser to trigger update

# Enterprise deployment update using Mozilla's update policies
# Create or modify policies.json in Firefox installation directory
cat > /usr/lib/firefox/distribution/policies.json << EOF
{
  "policies": {
    "DisableAppUpdate": false,
    "AppAutoUpdate": true
  }
}
EOF