diff --git a/requirements.txt b/requirements.txt
index 3b74c3a874..69d0c43bb1 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -21,3 +21,4 @@ cryptography>=2.0.2                     # BSD/Apache-2.0
 #
 # dnspython>=1.15.0;python_version=='2.7' # http://www.dnspython.org/LICENSE
 # ipaddress>=1.0.16;python_version<'3.3'  # PSF
+dnspython>=2.6.0rc1 # not directly required, pinned by Snyk to avoid a vulnerability