CVE-2024-2612 Overview
CVE-2024-2612 is a use-after-free vulnerability (CWE-416) in Mozilla's SafeRefPtr smart pointer implementation. An attacker who triggers a specific code path in SafeRefPtr can cause a crash or potentially achieve arbitrary code execution within the browser process. The vulnerability affects Firefox versions earlier than 124, Firefox ESR earlier than 115.9, and Thunderbird earlier than 115.9. Mozilla disclosed the issue in advisories MFSA-2024-12, MFSA-2024-13, and MFSA-2024-14, published on March 19, 2024. The flaw is network-accessible and requires no authentication or user interaction, though exploitation complexity is high.
Critical Impact
Successful exploitation can corrupt memory in the browser process, enabling remote code execution against unpatched Firefox, Firefox ESR, and Thunderbird clients that load attacker-controlled content.
Affected Products
- Mozilla Firefox versions earlier than 124
- Mozilla Firefox ESR versions earlier than 115.9
- Mozilla Thunderbird versions earlier than 115.9
Discovery Timeline
- 2024-03-19 - CVE-2024-2612 published to NVD with Mozilla advisories MFSA-2024-12, MFSA-2024-13, and MFSA-2024-14
- 2025-07-17 - Last updated in NVD database
Technical Details for CVE-2024-2612
Vulnerability Analysis
The vulnerability resides in Mozilla's SafeRefPtr, a reference-counted smart pointer used throughout the Gecko codebase to manage object lifetimes. Under a specific code path, SafeRefPtr releases or reuses an object reference while another code path still holds and dereferences the pointer. The resulting use-after-free condition allows an attacker to access freed heap memory and influence subsequent allocations.
Because SafeRefPtr is widely deployed across browser internals, exploitation can corrupt object metadata, virtual function tables, or callback pointers held in adjacent allocations. An attacker delivering crafted web content can groom the heap and steer the freed slot toward attacker-controlled data, converting the dangling reference into a controlled write or indirect call. This category of bug commonly chains with sandbox escape primitives to fully compromise the host.
Root Cause
The root cause is incorrect lifetime management within SafeRefPtr. A specific sequence of operations causes the reference count to drop while a live alias still references the underlying object. The freed memory is then accessed through that alias, satisfying the conditions for [CWE-416] Use After Free.
Attack Vector
Exploitation is remote and triggered through content rendered by the browser or mail client. An attacker hosts a malicious page or HTML email that drives the affected code path, then leverages the freed memory access to achieve crash conditions or code execution within the renderer process. No credentials or user interaction beyond loading the content are required, but the attack complexity is high because the attacker must reliably win the lifetime race and shape the heap.
A public exploit is not currently available, and the issue is not listed in the CISA Known Exploited Vulnerabilities catalog. Technical context is documented in Mozilla Bug 1879444.
Detection Methods for CVE-2024-2612
Indicators of Compromise
- Unexpected crashes of firefox.exe, firefox-bin, or thunderbird processes with access violation or SIGSEGV signals referencing heap addresses.
- Creation of crash dump files under the Mozilla Crash Reports directory immediately after rendering external web or email content.
- Spawning of unexpected child processes from a Firefox or Thunderbird parent process following a content load.
Detection Strategies
- Inventory installed Firefox, Firefox ESR, and Thunderbird versions across the fleet and flag any installation below the patched baselines (Firefox 124, Firefox ESR 115.9, Thunderbird 115.9).
- Correlate browser crash telemetry with recent network activity to identify clients repeatedly crashing after visiting the same origin.
- Monitor for renderer or content processes spawning command interpreters such as cmd.exe, powershell.exe, or /bin/sh, which would indicate a successful exploitation chain.
Monitoring Recommendations
- Collect Windows Error Reporting and crashreporter events into a central log pipeline and alert on clustered Mozilla process crashes.
- Subscribe to Mozilla security advisory feeds and the Debian LTS announcement list to track downstream package updates.
- Track outbound connections from browser processes to newly registered or low-reputation domains, especially when followed by process crashes.
How to Mitigate CVE-2024-2612
Immediate Actions Required
- Upgrade Firefox to version 124 or later, Firefox ESR to 115.9 or later, and Thunderbird to 115.9 or later on every endpoint and server.
- Deploy the corresponding Debian LTS packages on Linux systems using the updates referenced in Debian LTS Announcement #22 and Debian LTS Announcement #28.
- Force-restart browser and mail client sessions after patch deployment to ensure the vulnerable binary is unloaded from memory.
Patch Information
Mozilla released fixes in MFSA-2024-12, MFSA-2024-13, and MFSA-2024-14 on March 19, 2024. The fixed versions are Firefox 124, Firefox ESR 115.9, and Thunderbird 115.9. Downstream distributions including Debian shipped corresponding package updates.
Workarounds
- Disable JavaScript on untrusted origins through enterprise policy where business workflows allow.
- Configure Thunderbird to render messages as plain text and block remote content to limit attacker control over the rendering pipeline.
- Restrict browsing to trusted destinations through web proxy allow-listing until patching is completed.
# Verify installed versions on Linux endpoints
firefox --version
firefox-esr --version
thunderbird --version
# Example Debian patch deployment
sudo apt-get update
sudo apt-get install --only-upgrade firefox-esr thunderbird
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
