CVE-2025-2817: 
Mozilla Firefox vulnerability analysis and mitigation

CVE-2025-2817 is a high-severity privilege escalation vulnerability discovered in Mozilla Firefox and Thunderbird's update mechanism, disclosed on April 29, 2025. The vulnerability affects Firefox versions < 138, Firefox ESR < 128.10, Firefox ESR < 115.23, Thunderbird < 138, and Thunderbird < 128.10. The vulnerability was discovered by security researcher Dong-uk Kim (@justlikebono) (Mozilla Advisory).

The vulnerability exists in the update mechanism where a medium-integrity user process could interfere with the SYSTEM-level updater by manipulating the file-locking behavior. The vulnerability has been assigned a CVSS v3.1 base score of 8.8 (HIGH) with the vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. The vulnerability is classified as CWE-22 (Improper Limitation of a Pathname to a Restricted Directory) (NVD).

By exploiting this vulnerability, an attacker could bypass intended access controls by injecting code into the user-privileged process. This allows SYSTEM-level file operations on paths controlled by a non-privileged user, ultimately enabling privilege escalation (Mozilla Advisory).

Mozilla has addressed this vulnerability in Firefox 138, Firefox ESR 128.10, Firefox ESR 115.23, Thunderbird 138, and Thunderbird 128.10. Users are advised to update their installations to these or later versions to mitigate the vulnerability (Mozilla Advisory).