fix: tighten @org/name ref validation to prevent path traversal

Reject refs with multiple slashes (@org/a/b), dot segments (@../skill),
or leading dots in org/name. Applied to both CLI install() and SDK
parse_registry_ref() so the contract is enforced consistently.

lib/cli/src/crewai_cli/skills/main.py

@@ -92,16 +92,24 @@ class SkillCommand(BaseCommand, PlusAPIMixin):
             raise SystemExit(1)
 
         without_at = ref[1:]
-        if "/" not in without_at:
+        if without_at.count("/") != 1:
             console.print(
                 "[red]Invalid skill reference. Use the format @org/name.[/red]"
             )
             raise SystemExit(1)
 
-        org, _, name = without_at.partition("/")
-        if not org or not name:
+        org, name = without_at.split("/", 1)
+        if (
+            not org
+            or not name
+            or org.startswith(".")
+            or name.startswith(".")
+            or len(Path(org).parts) != 1
+            or len(Path(name).parts) != 1
+        ):
             console.print(
-                "[red]Invalid skill reference: org and name must be non-empty.[/red]"
+                "[red]Invalid skill reference: org and name must be single, "
+                "non-empty path segments (no slashes, no '..').[/red]"
             )
             raise SystemExit(1)
 

lib/crewai/src/crewai/skills/registry.py

@@ -48,14 +48,22 @@ def parse_registry_ref(ref: str) -> tuple[str, str]:
     if not ref.startswith("@"):
         raise ValueError(f"Registry reference must start with '@', got: {ref!r}")
     without_at = ref[1:]
-    if "/" not in without_at:
+    if without_at.count("/") != 1:
         raise ValueError(
             f"Registry reference must be in '@org/name' format, got: {ref!r}"
         )
-    org, _, name = without_at.partition("/")
-    if not org or not name:
+    org, name = without_at.split("/", 1)
+    if (
+        not org
+        or not name
+        or org.startswith(".")
+        or name.startswith(".")
+        or "/" in org
+        or "/" in name
+    ):
         raise ValueError(
-            f"Registry reference must have non-empty org and name, got: {ref!r}"
+            f"Registry reference org and name must be single, non-empty path "
+            f"segments (no '..' or leading dots), got: {ref!r}"
         )
     return org, name