diff --git a/lib/private/Security/Normalizer/IpAddress.php b/lib/private/Security/Normalizer/IpAddress.php
index 705235413e4..656487d8ce4 100644
--- a/lib/private/Security/Normalizer/IpAddress.php
+++ b/lib/private/Security/Normalizer/IpAddress.php
@@ -103,6 +103,8 @@ class IpAddress {
 				$this->ip,
 				32
 			);
+		} elseif (substr(strtolower($this->ip), 0, 7) === '::ffff:') {
+			return '::ffff:' . $this->getIPv4Subnet(substr($this->ip, 7), 32);
 		}
 		return $this->getIPv6Subnet(
 			$this->ip,
diff --git a/tests/lib/Security/Normalizer/IpAddressTest.php b/tests/lib/Security/Normalizer/IpAddressTest.php
index b202ecd7234..7492e182c32 100644
--- a/tests/lib/Security/Normalizer/IpAddressTest.php
+++ b/tests/lib/Security/Normalizer/IpAddressTest.php
@@ -38,6 +38,10 @@ class IpAddressTest extends TestCase {
 				'192.168.0.123',
 				'192.168.0.123/32',
 			],
+			[
+				'::ffff:192.168.0.123',
+				'::ffff:192.168.0.123/32',
+			],
 			[
 				'2001:0db8:85a3:0000:0000:8a2e:0370:7334',
 				'2001:db8:85a3::/64',