fix(security): prevent path traversal in session_store (#6876)

Validate that resolved session path stays within the sessions directory
using Path.is_relative_to(). Prevents session_id values like
"../../something" from escaping the sandbox.

Also guard the caller in _write_run_event where get_session_path is
called outside the existing OSError try/except block.

Fixes #1000

Co-authored-by: Sidhartha kumar <Alearner12@users.noreply.github.com>

core/framework/runtime/execution_stream.py

@@ -961,7 +961,10 @@ class ExecutionStream:
             return
         import json as _json
 
-        session_dir = self._session_store.get_session_path(execution_id)
+        try:
+            session_dir = self._session_store.get_session_path(execution_id)
+        except ValueError:
+            return
         runs_file = session_dir / "runs.jsonl"
         now = datetime.now()
         record = {

core/framework/storage/session_store.py

@@ -62,8 +62,14 @@ class SessionStore:
 
         Returns:
             Path to session directory
+
+        Raises:
+            ValueError: If session_id resolves outside the sessions directory
         """
-        return self.sessions_dir / session_id
+        resolved = (self.sessions_dir / session_id).resolve()
+        if not resolved.is_relative_to(self.sessions_dir.resolve()):
+            raise ValueError(f"Invalid session ID: {session_id}")
+        return resolved
 
     def get_state_path(self, session_id: str) -> Path:
         """

core/tests/test_path_traversal_fix.py

@@ -225,5 +225,28 @@ class TestPathTraversalWithActualFiles:
         assert run_file.exists()
 
 
+class TestSessionStorePathTraversal:
+    """Path traversal protection in SessionStore.get_session_path()."""
+
+    @pytest.fixture
+    def store(self, tmp_path):
+        from framework.storage.session_store import SessionStore
+
+        return SessionStore(tmp_path)
+
+    def test_valid_session_id(self, store):
+        path = store.get_session_path("session_20260206_143022_abc12345")
+        assert path.name == "session_20260206_143022_abc12345"
+
+    def test_blocks_parent_traversal(self, store):
+        with pytest.raises(ValueError, match="Invalid session ID"):
+            store.get_session_path("../../etc/passwd")
+
+    @pytest.mark.asyncio
+    async def test_delete_session_blocks_traversal(self, store):
+        with pytest.raises(ValueError, match="Invalid session ID"):
+            await store.delete_session("../../package")
+
+
 if __name__ == "__main__":
     pytest.main([__file__, "-v"])