This vulnerability (CVE-2026-13371) involves unsafe deserialization in the Fireware Management Web UI of WatchGuard Fireware OS. An authenticated administrator can send malformed or crafted data to the put_data endpoint, triggering a denial-of-service condition. The issue is classified under CWE-502 (Deserialization of Untrusted Data). The CVSS 4.0 base score is 6.9, indicating medium severity. No official patch or remediation guidance is currently provided by the vendor. The affected versions explicitly include 12.0, 12.5, and 2025.1.

An authenticated administrator can cause a denial-of-service condition in the Fireware Management Web UI, potentially disrupting management operations. There is no indication of remote unauthenticated exploitation or privilege escalation beyond administrator access. No known exploits are reported in the wild.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, restrict administrator access to trusted personnel only and monitor for unusual activity related to the put_data endpoint. Avoid sending untrusted or malformed data to the management interface.