CVE-2025-1012: 
NixOS vulnerability analysis and mitigation

CVE-2025-1012 is a security vulnerability discovered in Mozilla products, reported by security researcher Nils Bars. The vulnerability was disclosed on February 4, 2025, and affects multiple versions of Firefox and Thunderbird, specifically Firefox < 135, Firefox ESR < 115.20, Firefox ESR < 128.7, Thunderbird < 128.7, and Thunderbird < 135. The issue involves a race condition during concurrent delazification that could lead to a use-after-free vulnerability (Mozilla Advisory, NVD).

The vulnerability is classified as a use-after-free (CWE-416) issue that occurs during concurrent delazification processes. It has received a CVSS v3.1 base score of 7.5 (HIGH) from NVD with the vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H, indicating network accessibility with high attack complexity and requiring user interaction. CISA-ADP has assigned a higher CVSS score of 9.8 (CRITICAL) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H (NVD).

The vulnerability has been assessed with a moderate to high impact rating. If exploited, it could lead to memory corruption and potentially allow attackers to execute arbitrary code. The use-after-free condition could corrupt valid data if the memory area is reallocated, potentially resulting in system crashes or unauthorized code execution (Red Hat).

Mozilla has released security updates to address this vulnerability. Users should upgrade to Firefox 135.0, Firefox ESR 115.20, Firefox ESR 128.7, Thunderbird 128.7, or Thunderbird 135.0, depending on their product version. These updates have been confirmed to fix the vulnerability across all affected versions (Mozilla Advisory).