1 files changed, 3 insertions, 1 deletions
diff --git a/synapse/handlers/identity.py b/synapse/handlers/identity.py
index 000fbf090f..23f07832e7 100644
--- a/synapse/handlers/identity.py
+++ b/synapse/handlers/identity.py
@@ -38,7 +38,7 @@ from synapse.api.errors import (
 from synapse.config.emailconfig import ThreepidBehaviour
 from synapse.http.client import SimpleHttpClient
 from synapse.util.hash import sha256_and_url_safe_base64
-from synapse.util.stringutils import random_string
+from synapse.util.stringutils import assert_valid_client_secret, random_string
 
 from ._base import BaseHandler
 
@@ -84,6 +84,8 @@ class IdentityHandler(BaseHandler):
             raise SynapseError(
                 400, "Missing param client_secret in creds", errcode=Codes.MISSING_PARAM
             )
+        assert_valid_client_secret(client_secret)
+
         session_id = creds.get("sid")
         if not session_id:
             raise SynapseError(