CVE-2025-11714: Mozilla Firefox RCE Vulnerability

CVE-2025-11714 Overview

CVE-2025-11714 is a memory safety vulnerability affecting Mozilla Firefox and Thunderbird products. Memory safety bugs were identified in Firefox ESR 115.28, Firefox ESR 140.3, Thunderbird ESR 140.3, Firefox 143, and Thunderbird 143. Evidence of memory corruption was observed in some of these bugs, and Mozilla presumes that with sufficient effort, attackers could exploit them to achieve arbitrary code execution.

Critical Impact

This vulnerability enables potential arbitrary code execution through memory corruption, allowing attackers to compromise user systems when victims visit malicious web content or interact with crafted email messages.

Affected Products

• Mozilla Firefox versions prior to 144
• Mozilla Firefox ESR versions prior to 115.29 and 140.4
• Mozilla Thunderbird versions prior to 144 and 140.4

Discovery Timeline

• October 14, 2025 - CVE-2025-11714 published to NVD
• April 13, 2026 - Last updated in NVD database

Technical Details for CVE-2025-11714

Vulnerability Analysis

This vulnerability falls under CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer). The memory safety bugs present in affected Mozilla products indicate fundamental issues in how the browser engine manages memory operations. Memory corruption vulnerabilities of this nature typically arise from unsafe memory handling in the rendering engine or JavaScript interpreter components.

The vulnerability requires user interaction—specifically, a victim must navigate to a malicious webpage in Firefox or open a crafted email in Thunderbird. Once triggered, the memory corruption could allow an attacker to manipulate program execution flow, potentially leading to arbitrary code execution within the context of the user's session.

Root Cause

The root cause stems from improper restriction of operations within memory buffer boundaries. Multiple memory safety issues were discovered across the Mozilla codebase, suggesting systematic weaknesses in buffer management, pointer handling, or memory allocation routines. The Mozilla Bug List tracks the specific bugs (1973699, 1989945, 1990970, 1991040, 1992113) associated with this vulnerability.

Attack Vector

The attack vector is network-based, requiring user interaction. An attacker could exploit this vulnerability by:

1. Crafting a malicious webpage containing content that triggers the memory corruption
2. Luring a victim to visit the malicious site using Firefox
3. Alternatively, sending a malicious email that exploits the vulnerability when opened in Thunderbird

The memory corruption can be triggered through various browser components, and successful exploitation could result in arbitrary code execution with the privileges of the current user.

The vulnerability mechanism involves improper bounds checking during memory operations. When processing certain content, the affected applications fail to properly validate buffer boundaries, leading to memory corruption conditions. For detailed technical information, refer to the Mozilla Security Advisory MFSA-2025-81.

Detection Methods for CVE-2025-11714

Indicators of Compromise

• Unexpected Firefox or Thunderbird crashes, particularly when browsing specific websites or opening emails
• Unusual child process spawning from Firefox or Thunderbird parent processes
• Memory access violations or segmentation faults in browser logs
• Anomalous network connections initiated from browser processes

Detection Strategies

• Monitor for unusual process behavior from firefox.exe or thunderbird.exe including unexpected command execution
• Implement endpoint detection rules to identify memory corruption exploitation patterns
• Deploy network monitoring to detect connections to known malicious domains serving exploit payloads
• Review browser crash reports for patterns indicating memory safety exploitation attempts

Monitoring Recommendations

• Enable crash reporting and analyze Firefox/Thunderbird crash dumps for memory corruption signatures
• Monitor process creation events for suspicious child processes spawned by browser applications
• Implement application allowlisting to prevent unauthorized code execution from browser context
• Utilize SentinelOne's behavioral AI to detect post-exploitation activities following memory corruption attacks

How to Mitigate CVE-2025-11714

Immediate Actions Required

• Update Firefox to version 144 or Firefox ESR to versions 115.29 or 140.4 immediately
• Update Thunderbird to version 144 or 140.4 immediately
• Review and apply security updates from Linux distributions such as Debian (see Debian LTS Announcement #15 and Debian LTS Announcement #31)
• Restrict browser usage to trusted websites until patches are applied

Patch Information

Mozilla has released security patches addressing this vulnerability. Official security advisories with patch information are available:

• Mozilla Security Advisory MFSA-2025-81
• Mozilla Security Advisory MFSA-2025-82
• Mozilla Security Advisory MFSA-2025-83
• Mozilla Security Advisory MFSA-2025-84
• Mozilla Security Advisory MFSA-2025-85

Fixed versions: Firefox 144, Firefox ESR 115.29, Firefox ESR 140.4, Thunderbird 144, and Thunderbird 140.4.

Workarounds

• Disable JavaScript execution in Firefox via about:config by setting javascript.enabled to false (note: this will break most modern websites)
• Use browser isolation technologies to contain potential exploitation
• Configure email clients to view messages in plain text mode to reduce attack surface
• Implement network-level filtering to block access to known malicious domains

# Firefox update verification (Linux)
firefox --version
# Should display: Mozilla Firefox 144.0 or higher

# Thunderbird update verification (Linux)
thunderbird --version
# Should display: Mozilla Thunderbird 144.0 or higher