CVE-2025-10536 is an information disclosure vulnerability in the Networking: Cache component affecting Firefox and Thunderbird versions prior to Firefox 143 and Thunderbird 143, including Firefox ESR versions before 140.3. This vulnerability was fixed in Firefox 143 and Firefox ESR 140.3. It is part of a set of memory safety bugs addressed in these releases. The vulnerability has a CVSS score of 8.4, indicating high severity, but no known exploits in the wild have been reported.