Memory Handling Flaw in Firefox and Thunderbird from Mozilla

CVE-2025-8027

What is CVE-2025-8027?

CVE-2025-8027 is a memory handling vulnerability found in Firefox and Thunderbird, both products developed by Mozilla. This flaw arises from the mishandling of 64-bit return values in the IonMonkey Just-In-Time (JIT) compilation process, where only 32 bits are written to the stack instead of the expected 64 bits. As a result, when the Baseline-JIT attempts to read the return value, it retrieves the incomplete data, leading to unpredictable behavior. Such vulnerabilities can significantly harm organizations by potentially enabling various attacks, including information leakage and unauthorized access to sensitive data. The affected versions of Firefox include those prior to 141, as well as specific Extended Support Release (ESR) variants. Thunderbird is similarly impacted in versions below 141 and its respective ESR releases.

Potential Impact of CVE-2025-8027

1. Unauthorized Access: The vulnerability could allow attackers to manipulate return values and access restricted memory areas, potentially leading to unauthorized execution of code in the context of the user running the affected application.

2. Data Leakage: Incomplete stack write operations might expose sensitive information stored in memory by enabling attackers to read memory contents that should be protected, which could result in data breaches.

3. System Instability: Exploiting this vulnerability may cause application crashes or lead to unstable system behavior, disrupting normal operations for users and increasing the burden on IT support and recovery efforts.

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