CVE-2023-32216: Mozilla Firefox RCE Vulnerability

CVE-2023-32216 Overview

CVE-2023-32216 is a memory safety vulnerability affecting Mozilla Firefox versions before 113. Mozilla developers and community members reported multiple memory safety bugs present in Firefox 112. Some of these bugs showed evidence of memory corruption. Mozilla assessed that with sufficient effort, attackers could leverage some of these flaws to execute arbitrary code in the browser process.

The vulnerability is classified under [CWE-787] (Out-of-Bounds Write) and is exploitable remotely without authentication or user interaction beyond visiting a crafted page.

Critical Impact
Successful exploitation could allow remote attackers to execute arbitrary code within the Firefox process, leading to full compromise of confidentiality, integrity, and availability on affected systems.

Affected Products

Mozilla Firefox versions prior to 113
Linux distributions packaging Firefox < 113 (see Gentoo GLSA 202401-10)
Any platform shipping Firefox 112 or earlier as a bundled or default browser

Discovery Timeline

2023-06-19 - CVE-2023-32216 published to the National Vulnerability Database
2025-05-27 - Last updated in NVD database

Technical Details for CVE-2023-32216

Vulnerability Analysis

The advisory aggregates multiple memory safety defects identified in Firefox 112 by Mozilla developers and the Mozilla Fuzzing Team. Reporters named in the advisory include Ronald Crane, Andrew McCreight, and Randell Jesup. Mozilla grouped these issues under a single CVE because they share the same root category and remediation path.

The defects are categorized as out-of-bounds writes ([CWE-787]). At least a subset of the bugs showed evidence of memory corruption during fuzzing and triage. Memory corruption in a browser engine typically allows attackers to overwrite adjacent heap structures, manipulate object metadata, or hijack control flow during JavaScript or rendering operations.

Root Cause

The underlying cause is improper handling of memory boundaries in components of the Gecko engine touched by Firefox 112. The specific subsystems are tracked in the linked Bugzilla entries (1746479, 1806852, 1815987, 1820359, 1823568, 1824803, 1824834, 1825170, 1827020, 1828130). Mozilla does not publish exploitation details for these reports while users migrate to fixed versions.

Attack Vector

An attacker hosts a malicious or compromised web page containing crafted content that triggers the memory corruption when Firefox parses or renders it. The victim only needs to load the page in a vulnerable browser. No credentials, prompts, or additional clicks are required after navigation. Successful exploitation runs attacker-controlled code inside the browser's content or parent process.

No verified public proof-of-concept is available for CVE-2023-32216. See the Mozilla Security Advisory MFSA-2023-16 and the linked Mozilla Bug Reports for technical references.

Detection Methods for CVE-2023-32216

Indicators of Compromise

Firefox process crashes or unexpected child-process terminations correlated with browsing activity
Browser telemetry showing repeated renderer crashes on specific domains
Unexpected child processes spawned by firefox.exe or firefox-bin following web navigation
Outbound connections from the Firefox process to unfamiliar hosts after visiting untrusted sites

Detection Strategies

Inventory installed Firefox versions across managed endpoints and flag any build prior to 113
Monitor endpoint logs for process-injection or unexpected child processes originating from the Firefox binary
Correlate web proxy logs with crash telemetry to identify pages triggering memory faults

Monitoring Recommendations

Centralize browser version inventory and crash telemetry for continuous visibility
Alert on Firefox spawning command interpreters such as cmd.exe, powershell.exe, or /bin/sh
Track outbound traffic from browser processes to newly registered or low-reputation domains
Review patch compliance dashboards weekly to confirm Firefox 113 or later is deployed

How to Mitigate CVE-2023-32216

Immediate Actions Required

Upgrade Mozilla Firefox to version 113 or later on all managed and unmanaged endpoints
Apply distribution-specific updates such as the fixes covered by Gentoo GLSA 202401-10
Restart Firefox after applying updates to ensure the patched binaries are loaded
Validate update deployment through software inventory tooling

Patch Information

Mozilla released the fix in Firefox 113. Details are documented in the Mozilla Security Advisory MFSA-2023-16. Linux users should consult their distribution advisories, including Gentoo GLSA 202401-10, for package-level updates.

Workarounds

Restrict Firefox usage to trusted internal sites until patching is complete
Enforce browser isolation or remote browser technologies for users who must access untrusted content
Deploy enterprise policies that block JavaScript execution on untrusted domains where feasible
Use network egress filtering and reputation-based web proxies to reduce exposure to malicious pages

bash

# Verify installed Firefox version on Linux
firefox --version

# Example: enforce minimum version policy via Ansible
- name: Ensure Firefox is at or above 113
  package:
    name: firefox
    state: latest