CVE-2025-10533 is an integer overflow vulnerability identified in the SVG component of Mozilla Firefox and Thunderbird products. The flaw could potentially lead to memory corruption or other unintended behavior. Mozilla fixed this vulnerability in Firefox 143, Firefox ESR 115.28, Firefox ESR 140.3, Thunderbird 143, and Thunderbird 140.3. The CVSS v3.1 base score is 8.8, reflecting high severity with network attack vector, low attack complexity, requiring low privileges, no user interaction, and high impact on confidentiality, integrity, and availability. The vendor advisory classifies the impact as moderate and confirms the vulnerability is addressed in the stated versions.

The vulnerability could allow an attacker to cause memory corruption or other adverse effects through an integer overflow in the SVG component, potentially impacting confidentiality, integrity, and availability of the affected software. However, no known exploits in the wild have been reported. The CVSS score of 8.8 indicates a high severity risk if unpatched. The vendor advisory rates the impact as moderate and confirms the issue is fixed in recent Firefox and Thunderbird releases.

Official fixes for this vulnerability are available in Firefox 143, Firefox ESR 115.28, Firefox ESR 140.3, Thunderbird 143, and Thunderbird 140.3. Users and administrators should update to these versions or later to remediate the vulnerability. Since the vendor advisory confirms the availability of patches, applying these updates is the recommended mitigation. No additional mitigation steps are indicated by the vendor.