This vulnerability (CVE-2025-25253) is due to improper validation of certificates when there is a host mismatch in Fortinet FortiProxy versions 7.6.1 and below, 7.4.8 and below, all versions of 7.2 and 7.0, and FortiOS versions 7.6.2 and below, 7.4.8 and below, all versions of 7.2 and 7.0 ZTNA proxy. An unauthenticated attacker in a man-in-the-middle position could exploit this flaw to intercept and tamper with connections to the ZTNA proxy, potentially leading to information disclosure and manipulation of data in transit. The CVSS 3.1 vector indicates the attack requires adjacent network access with high attack complexity, no privileges or user interaction, and impacts confidentiality, integrity, and availability with partial exploit code maturity and a revised report confidence.

An attacker with adjacent network access can intercept and modify traffic between clients and the ZTNA proxy due to improper certificate validation. This can lead to disclosure of sensitive information and tampering with data, impacting confidentiality, integrity, and availability of communications through the affected FortiProxy and FortiOS ZTNA proxy versions.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. No official fix or patch links are provided in the available data. Until a patch is available, organizations should consider network-level mitigations to prevent man-in-the-middle positioning and monitor for suspicious activity related to ZTNA proxy connections.