{
  "same_root_cause": true,
  "confidence": "high",
  "explanation": "All three alternate triggers reach the same vulnerable sink: send_ssi_file() in src/civetweb.c detects the SSI #exec directive and calls do_ssi_exec(), which passes the attacker-controlled command string to popen(). The command execution happens regardless of whether the .shtml file was created by a Content-Length PUT, a chunked PUT, a WebDAV MOVE, or a PUT to the .shtm extension. The same configuration options (put_delete_auth_file, ssi_pattern) and the same popen() sink are involved in every variant.",
  "shared_files": ["src/civetweb.c"],
  "shared_functions": ["put_file", "dav_move_file", "send_ssi_file", "do_ssi_exec"],
  "shared_configuration": ["put_delete_auth_file", "ssi_pattern", "enable_webdav"],
  "distinguishing_factors": [
    "HTTP body framing differs (Content-Length vs Transfer-Encoding: chunked) but is handled by the same forward_body_data() path",
    "WebDAV MOVE uses dav_move_file() instead of a direct PUT, but the resulting file on disk is identical",
    ".shtm is matched by the same default ssi_pattern as .shtml"
  ]
}