diff --git a/ruian-swagger/requirements.txt b/ruian-swagger/requirements.txt
index a964cf8..f20a4d9 100644
--- a/ruian-swagger/requirements.txt
+++ b/ruian-swagger/requirements.txt
@@ -16,3 +16,4 @@ dicttoxml~=1.7.4
 lat-lon-parser==1.2.0
 gunicorn==23.0.0
 Flask-Cors==3.0.10
+marshmallow>=3.26.2 # not directly required, pinned by Snyk to avoid a vulnerability