ZDI-26-749: WatchGuard FireWare OS samld SAMLSession Deserialization of Untrusted Data Remote Code Execution Vulnerability
This vulnerability allows remote attackers to execute arbitrary code on affected installations of WatchGuard FireWare OS. An attacker must first obtain the ability to write to the samld session directory on the target system in order to exploit this vulnerability.
The specific flaw exists within the handling of session files in the samld service. The issue results from the lack of proper validation of user-supplied data, which can result in deserialization of untrusted data. An attacker can leverage this in conjunction with other vulnerabilities to execute code in the context of the samld user.
WatchGuard has issued an update to correct this vulnerability. More details can be found at:
2026-05-22 - Vulnerability reported to vendor
2026-09-30 - Coordinated public release of advisory
2026-09-30 - Advisory Updated
Nicholas Zubrisky (@NZubrisky) of TrendAI Research
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