The vulnerability allows a user with PERM_WRITE privileges to inject arbitrary Asterisk directives into extensions_custom.conf through the fm_dialplan_apply API endpoint. It results from failing to escape Dialplan template parameters, except for contextName which is sanitized. Attackers can execute system-level commands via System(), Set(SHELL(...)), or alter call flow using Goto or Macro, leading to remote code execution. The weakness corresponds to code injection and improper input validation.

This issue affects installations of Frogman prior to version 1.6.2. Vendors such as mwtcmi that provide Frogman are impacted, especially when the API or MCP is reachable by untrusted users. Any instance running a Frogman build older than 1.6.2 with API access is vulnerable.

The CVSS score of 9.9 marks the flaw as critical. Although the EPSS score is under 1%, indicating a low but nonzero exploitation probability, the flaw is not listed in CISA’s KEV catalog. Attackers can exploit the vulnerability over the network through the HTTP API or MCP interface, provided they possess a privileged role that can set confirm:true. Once injected, the unescaped directives are executed by Asterisk with the same privileges as the Frogman process, effectively granting remote code execution.