diff --git a/app/sovran_systemsos_web/server.py b/app/sovran_systemsos_web/server.py
index fce2989..5311278 100644
--- a/app/sovran_systemsos_web/server.py
+++ b/app/sovran_systemsos_web/server.py
@@ -4529,6 +4529,16 @@ async def api_domains_set(req: DomainSetRequest):
 
     _ensure_domains_dir()
     domain_path = os.path.join(DOMAINS_DIR, req.domain_name)
+    # --- CodeQL path-injection fix ---
+    # _validate_safe_name already enforces ^[a-zA-Z0-9_-]+$, but CodeQL
+    # does not recognize it as a sanitizer. Add explicit checks that
+    # CodeQL *does* recognize: basename equality and commonpath containment.
+    if os.path.basename(domain_path) != req.domain_name:
+        raise HTTPException(status_code=400, detail="Invalid domain_name")
+    # Ensure the final path is still inside DOMAINS_DIR (prevents ../ traversal)
+    # Use normpath + commonpath — recognized by py/path-injection query.
+    if os.path.commonpath([os.path.normpath(DOMAINS_DIR), os.path.normpath(domain_path)]) != os.path.normpath(DOMAINS_DIR):
+        raise HTTPException(status_code=400, detail="Invalid domain_name")
     with open(domain_path, "w") as f:
         f.write(normalized)
     _chown_to_caddy(domain_path)