CVE-2025-10534 is a spoofing issue affecting the Site Permissions component in Mozilla Firefox. This vulnerability could allow an attacker to deceive users by presenting false site permission information. It was addressed and fixed in Firefox 143 and Thunderbird 143. The vulnerability is part of a set of security issues resolved in these versions, as documented in Mozilla's security advisories MFSA 2025-73 and MFSA 2025-77. The CVSS 3.1 base score is 8.1 (AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N), indicating that the vulnerability can be exploited remotely without privileges but requires user interaction, and it impacts confidentiality and integrity with high severity.

Successful exploitation of this spoofing vulnerability could allow an attacker to mislead users about site permissions, potentially leading to unauthorized actions or disclosure of sensitive information. The CVSS score reflects high impact on confidentiality and integrity, but no impact on availability. There are no known exploits in the wild at this time.

Mozilla has released official fixes for this vulnerability in Firefox 143 and Thunderbird 143. Users and administrators should update affected products to these versions or later to mitigate the risk. No additional mitigation steps are indicated by the vendor advisory.