diff --git a/sigma/validators/core/tags.py b/sigma/validators/core/tags.py
index 746d00fc..94d6c43b 100644
--- a/sigma/validators/core/tags.py
+++ b/sigma/validators/core/tags.py
@@ -180,7 +180,7 @@ class InvalidNamespaceTagIssue(SigmaValidationIssue):
 class NamespaceTagValidator(SigmaTagValidator):
     """Validate rule tag name"""
 
-    allowed_namespace = {"attack", "car", "cve", "detection", "stp"}
+    allowed_namespace = {"attack", "car", "stp", "cve", "tlp", "detection"}
 
     def validate_tag(self, tag: SigmaRuleTag) -> List[SigmaValidationIssue]:
         if tag.namespace not in self.allowed_namespace:
diff --git a/tests/test_validators_tags.py b/tests/test_validators_tags.py
index e6d3d975..2086ff64 100644
--- a/tests/test_validators_tags.py
+++ b/tests/test_validators_tags.py
@@ -178,7 +178,19 @@ def test_validator_duplicate_tags():
             ["attaque.command_and_control"],
             InvalidNamespaceTagIssue,
         ),
-        (NamespaceTagValidator, ["cve.2023.007"], [], InvalidNamespaceTagIssue),
+        (
+            NamespaceTagValidator,
+            [
+                "attack.t1234",
+                "car.2016-04-005",
+                "stp.3k",
+                "cve.2023.007",
+                "tlp.amber",
+                "detection.threat_hunting",
+            ],
+            [],
+            InvalidNamespaceTagIssue,
+        ),
     ],
 )
 def test_validator_optional_tag(opt_validator_class, opt_tags, opt_issue_tags, opt_issue_class):