CVE-2025-1930: Mozilla Firefox Use-After-Free Vulnerability

CVE-2025-1930 Overview

CVE-2025-1930 is a use-after-free vulnerability affecting Mozilla Firefox and Thunderbird on Windows systems. A compromised content process can exploit malformed StreamData sent over AudioIPC to trigger a use-after-free condition in the Browser process. This memory corruption vulnerability could potentially enable an attacker to escape the browser sandbox, representing a serious security concern for affected users.

Critical Impact

This vulnerability enables sandbox escape on Windows, allowing malicious code to break out of Firefox/Thunderbird's security containment and potentially execute arbitrary code with elevated privileges.

Affected Products

• Mozilla Firefox versions prior to 136
• Mozilla Firefox ESR versions prior to 115.21 and 128.8
• Mozilla Thunderbird versions prior to 136 and 128.8

Discovery Timeline

• 2025-03-04 - CVE-2025-1930 published to NVD
• 2026-04-13 - Last updated in NVD database

Technical Details for CVE-2025-1930

Vulnerability Analysis

This vulnerability resides in the inter-process communication (IPC) mechanism used for audio processing in Mozilla applications. Firefox and Thunderbird employ a multi-process architecture where content processes are sandboxed to limit the impact of security compromises. The AudioIPC component facilitates communication between the sandboxed content process and the privileged browser process for audio playback functionality.

The flaw manifests when a compromised content process sends specially crafted StreamData over the AudioIPC channel. The browser process fails to properly validate or handle this malformed data, leading to a use-after-free condition where memory that has been freed is subsequently accessed. This type of memory corruption can allow an attacker who has already compromised the content process to escalate their privileges by escaping the sandbox.

Root Cause

The root cause is a use-after-free vulnerability (CWE-416) in the AudioIPC handling code within the browser process. When processing StreamData from content processes, the browser process does not adequately ensure memory integrity, allowing freed memory to be dereferenced. This occurs because the lifecycle management of audio stream objects is not properly synchronized with incoming IPC messages, creating a window where stale pointers can be exploited.

Attack Vector

The attack requires the adversary to first compromise a content process through another vulnerability or attack vector (such as a renderer exploit via malicious web content). Once the content process is controlled, the attacker can send malicious StreamData payloads through the AudioIPC channel to the browser process. The malformed data triggers the use-after-free, potentially allowing arbitrary code execution in the context of the browser process, which operates outside the sandbox with higher privileges.

The vulnerability is exploited over the network attack vector, requiring user interaction (such as visiting a malicious website). When successfully exploited, it can lead to complete compromise of confidentiality, integrity, and availability of the affected system.

Detection Methods for CVE-2025-1930

Indicators of Compromise

• Unexpected crashes or instability in Firefox or Thunderbird browser processes on Windows systems
• Anomalous audio-related IPC activity in process monitoring logs
• Detection of suspicious child processes spawned from Firefox or Thunderbird with elevated privileges
• Memory access violations or exceptions in the browser process related to audio subsystems

Detection Strategies

• Monitor for unusual process behavior from Firefox/Thunderbird, particularly child process spawning with elevated privileges
• Implement endpoint detection rules for use-after-free exploitation patterns in browser processes
• Deploy behavioral analysis to detect sandbox escape attempts from content processes
• Utilize crash telemetry to identify exploitation attempts manifesting as specific crash signatures

Monitoring Recommendations

• Enable enhanced logging for browser process crashes and audit for patterns indicating exploitation
• Monitor system calls and API usage from browser processes for sandbox escape indicators
• Implement network monitoring to detect access to known malicious domains that may serve exploit payloads
• Review Windows Event Logs for application crashes and memory access violations in Mozilla products

How to Mitigate CVE-2025-1930

Immediate Actions Required

• Update Mozilla Firefox to version 136 or later immediately
• Update Mozilla Firefox ESR to version 115.21 or 128.8 or later
• Update Mozilla Thunderbird to version 136 or 128.8 or later
• Verify all Windows systems running affected Mozilla products are patched

Patch Information

Mozilla has released security patches addressing this vulnerability across multiple product versions. Users should update to the following fixed versions:

• Firefox 136 - Mozilla Security Advisory MFSA-2025-14
• Firefox ESR 115.21 - Mozilla Security Advisory MFSA-2025-15
• Firefox ESR 128.8 - Mozilla Security Advisory MFSA-2025-16
• Thunderbird 136 - Mozilla Security Advisory MFSA-2025-17
• Thunderbird 128.8 - Mozilla Security Advisory MFSA-2025-18

For technical details, see Mozilla Bug Report #1902309.

Workarounds

• If immediate patching is not possible, consider temporarily restricting access to untrusted websites
• Implement network-level controls to limit exposure to potentially malicious content
• Deploy application control policies to restrict browser functionality in high-risk environments
• Consider using alternative browsers on Windows systems until patches can be applied

# Verify Firefox/Thunderbird version on Windows (PowerShell)
# Check Firefox version
Get-ItemProperty "HKLM:\SOFTWARE\Mozilla\Mozilla Firefox" | Select-Object -ExpandProperty CurrentVersion

# Check Thunderbird version  
Get-ItemProperty "HKLM:\SOFTWARE\Mozilla\Mozilla Thunderbird" | Select-Object -ExpandProperty CurrentVersion

# Force update check via Firefox
firefox.exe -update