CVE-2024-2607: Mozilla Firefox RCE Vulnerability

CVE-2024-2607 Overview

CVE-2024-2607 is a memory corruption vulnerability in Mozilla Firefox, Firefox Extended Support Release (ESR), and Thunderbird. Return registers were overwritten during code generation, which could allow an attacker to execute arbitrary code. The issue only affects Armv7-A systems; other platforms are unaffected. The vulnerability impacts Firefox versions earlier than 124, Firefox ESR earlier than 115.9, and Thunderbird earlier than 115.9. Debian Linux distributions packaging these Mozilla products also inherit the exposure. The flaw is tracked under [CWE-123] (Write-what-where Condition).

Critical Impact
A remote attacker can achieve arbitrary code execution on Armv7-A systems running a vulnerable Mozilla client by inducing the user to load attacker-controlled web content.

Affected Products

Mozilla Firefox versions earlier than 124
Mozilla Firefox ESR versions earlier than 115.9 and Mozilla Thunderbird versions earlier than 115.9
Debian Linux 10.0 packages distributing the affected Mozilla builds

Discovery Timeline

2024-03-19 - CVE-2024-2607 published to NVD
2025-04-01 - Last updated in NVD database

Technical Details for CVE-2024-2607

Vulnerability Analysis

The vulnerability resides in the Armv7-A code generation path used by Mozilla's runtime. During execution, return registers were overwritten in a manner that an attacker could influence. By controlling the values placed into these registers, an adversary can redirect control flow at function return. This produces an arbitrary code execution primitive within the browser or mail client process.

The attack vector is network-based and requires no privileges. The attack complexity is rated high because exploitation depends on the victim running an Armv7-A build, which narrows the target population. Successful exploitation compromises confidentiality, integrity, and availability of the affected process.

Root Cause

The root cause is improper handling of return register state on the 32-bit ARM (Armv7-A) architecture. The defect is classified under [CWE-123] Write-what-where Condition, allowing controlled data to overwrite control-flow values. Refer to the Mozilla Bugzilla Report for technical specifics.

Attack Vector

An attacker hosts crafted web content that triggers the affected code generation path when rendered by Firefox, Firefox ESR, or Thunderbird on Armv7-A. When the vulnerable function returns, attacker-influenced register state diverts execution to attacker-chosen instructions. Thunderbird users are exposed when remote content is loaded in messages. No authentication or user interaction beyond visiting the content is required.

No verified public proof-of-concept code is available for this issue. See Mozilla Security Advisory MFSA-2024-12 for vendor analysis.

Detection Methods for CVE-2024-2607

Indicators of Compromise

Firefox, Firefox ESR, or Thunderbird processes on Armv7-A devices spawning unexpected child processes or shells
Unexplained outbound network connections originating from the browser or mail client process after rendering untrusted content
Crash reports or signal handler entries referencing memory faults in JIT-generated code regions on ARM endpoints

Detection Strategies

Inventory all Armv7-A endpoints and identify installed Mozilla product versions, flagging any below Firefox 124, Firefox ESR 115.9, or Thunderbird 115.9
Monitor process lineage from firefox, firefox-esr, and thunderbird for anomalous child processes such as shells or scripting interpreters
Correlate browser crash telemetry on ARM devices with subsequent network or filesystem activity that deviates from baseline behavior

Monitoring Recommendations

Forward endpoint process, network, and crash telemetry from ARM devices into a centralized analytics platform for correlation
Alert on execution of unsigned binaries or scripts spawned by Mozilla product processes
Track package management events on Debian systems referencing the Debian LTS Security Announcement for affected Mozilla packages

How to Mitigate CVE-2024-2607

Immediate Actions Required

Upgrade Firefox to version 124 or later on all Armv7-A endpoints
Upgrade Firefox ESR and Thunderbird to version 115.9 or later
Apply Debian security updates for affected Mozilla packages on Debian 10 systems per the Debian LTS Security Announcement
Restrict Armv7-A endpoints from rendering untrusted web content until patches are deployed

Patch Information

Mozilla addressed this issue in Firefox 124, Firefox ESR 115.9, and Thunderbird 115.9. Vendor details are available in Mozilla Security Advisory MFSA-2024-12, Mozilla Security Advisory MFSA-2024-13, and Mozilla Security Advisory MFSA-2024-14. Debian users should install the updated packages distributed through the Debian LTS security channel.

Workarounds

Disable JavaScript in Thunderbird message rendering until patched versions are deployed
Migrate users from Armv7-A hardware to 64-bit ARM (AArch64) or x86_64 platforms, which are not affected by this issue
Apply network-level filtering to block access to untrusted web origins from unpatched ARM endpoints

bash

# Configuration example - upgrade affected Mozilla packages on Debian
sudo apt-get update
sudo apt-get install --only-upgrade firefox-esr thunderbird

# Verify installed versions meet the fixed baseline
firefox-esr --version    # expect >= 115.9
thunderbird --version    # expect >= 115.9