diff --git a/backend/secuscan/plugin_validator.py b/backend/secuscan/plugin_validator.py
index ad6aefa7e..0a9fe955b 100644
--- a/backend/secuscan/plugin_validator.py
+++ b/backend/secuscan/plugin_validator.py
@@ -285,13 +285,49 @@ def _check_validation_block(self, data: dict, result: ValidationResult) -> None:
             result.add("validation", "Must be an object if present")
             return
 
+        field_ids = {
+            field.get("id")
+            for field in data.get("fields", [])
+            if isinstance(field, dict)
+        }
+
         for key, rule in validation.items():
             prefix = f"validation.{key}"
+
             if not isinstance(rule, dict):
                 result.add(prefix, "Each validation rule must be an object")
                 continue
+
             if "required" in rule and not isinstance(rule["required"], bool):
-                result.add(f"{prefix}.required", "'required' must be a boolean")
+                result.add(
+                    f"{prefix}.required",
+                    "'required' must be a boolean",
+                )
+
+            mutually_exclusive = rule.get("mutually_exclusive")
+
+            if mutually_exclusive is None:
+                continue
+
+            if not isinstance(mutually_exclusive, list):
+                result.add(
+                    f"{prefix}.mutually_exclusive",
+                    "'mutually_exclusive' must be a list",
+                )
+                continue
+
+            if len(mutually_exclusive) < 2:
+                result.add(
+                    f"{prefix}.mutually_exclusive",
+                    "Must contain at least two field ids",
+                )
+
+            for field_id in mutually_exclusive:
+                if field_id not in field_ids:
+                    result.add(
+                        f"{prefix}.mutually_exclusive",
+                        f"Unknown field '{field_id}'",
+                    )
 
     def _check_checksum(self, data: dict, result: ValidationResult) -> None:
         checksum = data.get("checksum")
diff --git a/plugins/ssh_runner/metadata.json b/plugins/ssh_runner/metadata.json
index 6673d75ad..a0af53824 100644
--- a/plugins/ssh_runner/metadata.json
+++ b/plugins/ssh_runner/metadata.json
@@ -50,6 +50,20 @@
       "required": true,
       "default": "uptime",
       "help": "Command to execute on the remote host."
+    },
+    {
+      "id": "password",
+      "label": "Password",
+      "type": "string",
+      "required": false,
+      "help": "Password-based SSH authentication."
+    },
+    {
+      "id": "private_key",
+      "label": "Private Key",
+      "type": "string",
+      "required": false,
+      "help": "Path to SSH private key."
     }
   ],
   "presets": {
@@ -60,6 +74,14 @@
       "command": "cat /var/log/auth.log | tail -n 20"
     }
   },
+  "validation": {
+    "authentication": {
+      "mutually_exclusive": [
+        "password",
+        "private_key"
+      ]
+    }
+  },
   "output": {
     "format": "text",
     "parser": "custom"
@@ -88,5 +110,5 @@
     ]
   },
   "docker_image": "alpine:latest",
-  "checksum": "6d4495f58635dedb184e763e0e4467adf17dc3754a6b1ed7c2dca0d6b30a88ec"
+  "checksum": "76f62464b0e9fb8e0322b52461dae8029053769f60da9b4ce8f73604b7048aaa"
 }
diff --git a/testing/backend/unit/test_plugin_validator.py b/testing/backend/unit/test_plugin_validator.py
index 0cdc69c27..d390c2079 100644
--- a/testing/backend/unit/test_plugin_validator.py
+++ b/testing/backend/unit/test_plugin_validator.py
@@ -600,3 +600,72 @@ def test_missing_category_is_not_flagged(self, tmp_path):
         cat_errors = [e for e in result.errors if e.path == "category"]
         assert len(cat_errors) == 1
         assert "Required" in cat_errors[0].message
+
+    def test_mutually_exclusive_fields_must_reference_existing_fields(self, tmp_path):
+        data = _minimal_valid()
+        data["fields"] = [
+            {
+                "id": "password",
+                "label": "Password",
+                "type": "text",
+                "help": "Password authentication",
+            },
+            {
+                "id": "private_key",
+                "label": "Private Key",
+                "type": "text",
+                "help": "SSH private key",
+            },
+        ]
+        data["validation"] = {
+            "authentication": {
+                "mutually_exclusive": [
+                    "password",
+                    "private_key",
+                ]
+            }
+        }
+
+        plugin_dir = _write_metadata(tmp_path, data)
+        result = validate_one_plugin(plugin_dir)
+
+        mutually_exclusive_errors = [
+            e
+            for e in result.errors
+            if "mutually_exclusive" in e.path
+        ]
+
+        assert mutually_exclusive_errors == []
+
+    def test_mutually_exclusive_fields_unknown_field_is_rejected(self, tmp_path):
+        data = _minimal_valid()
+        data["fields"] = [
+            {
+                "id": "password",
+                "label": "Password",
+                "type": "text",
+                "help": "Password authentication",
+            },
+        ]
+        data["validation"] = {
+            "authentication": {
+                "mutually_exclusive": [
+                    "password",
+                    "private_key",
+                ]
+            }
+        }
+
+        plugin_dir = _write_metadata(tmp_path, data)
+        result = validate_one_plugin(plugin_dir)
+
+        assert not result.valid
+
+        mutually_exclusive_errors = [
+            e
+            for e in result.errors
+            if "mutually_exclusive" in e.path
+        ]
+
+        assert len(mutually_exclusive_errors) == 1
+        assert "private_key" in mutually_exclusive_errors[0].message