diff --git a/ipn/ipnlocal/peerapi.go b/ipn/ipnlocal/peerapi.go
index bf9708751..a02ee2e40 100644
--- a/ipn/ipnlocal/peerapi.go
+++ b/ipn/ipnlocal/peerapi.go
@@ -136,6 +136,9 @@ func (s *peerAPIServer) diskPath(baseName string) (fullPath string, ok bool) {
 			return "", false
 		}
 	}
+	if !filepath.IsLocal(baseName) {
+		return "", false
+	}
 	return filepath.Join(s.rootDir, baseName), true
 }