diff --git a/components/ILIAS/CmiXapi/classes/class.ilCmiXapiAuthToken.php b/components/ILIAS/CmiXapi/classes/class.ilCmiXapiAuthToken.php
index 2898c0430c76..3f7100f0cd1d 100755
--- a/components/ILIAS/CmiXapi/classes/class.ilCmiXapiAuthToken.php
+++ b/components/ILIAS/CmiXapi/classes/class.ilCmiXapiAuthToken.php
@@ -248,7 +248,7 @@ public static function selectCurrentTimestamp(): string
 
     public static function createToken(): string
     {
-        return (new \Ramsey\Uuid\UuidFactory())->uuid4()->toString();
+        return (new \ILIAS\Data\UUID\Factory())->uuid4AsString();
     }
 
     public static function fillToken(int $usrId, int $refId, int $objId, int $lrsTypeId = 0): string
diff --git a/components/ILIAS/CmiXapi/classes/class.ilCmiXapiContentUploadImporter.php b/components/ILIAS/CmiXapi/classes/class.ilCmiXapiContentUploadImporter.php
index ac9ff45ef5ef..1dda53609647 100755
--- a/components/ILIAS/CmiXapi/classes/class.ilCmiXapiContentUploadImporter.php
+++ b/components/ILIAS/CmiXapi/classes/class.ilCmiXapiContentUploadImporter.php
@@ -460,6 +460,6 @@ private function generateActivityId(string $publisherId): string
     {
         global $DIC;
         $objId = $this->object->getId();
-        return "https://ilias.de/cmi5/activityid/" . (new \Ramsey\Uuid\UuidFactory())->uuid3(ilCmiXapiUser::getIliasUuid(), $objId . '-' . $publisherId);
+        return "https://ilias.de/cmi5/activityid/" . (new \ILIAS\Data\UUID\Factory())->uuid3AsString(ilCmiXapiUser::getIliasUuid(), $objId . '-' . $publisherId);
     }
 }
diff --git a/components/ILIAS/CmiXapi/classes/class.ilCmiXapiUser.php b/components/ILIAS/CmiXapi/classes/class.ilCmiXapiUser.php
index 528d288bf11e..79585d2521b5 100755
--- a/components/ILIAS/CmiXapi/classes/class.ilCmiXapiUser.php
+++ b/components/ILIAS/CmiXapi/classes/class.ilCmiXapiUser.php
@@ -18,6 +18,9 @@
 
 declare(strict_types=1);
 
+use ILIAS\Data\UUID\Factory as UuidFactory;
+use ILIAS\Data\UUID\Uuid;
+
 /**
  * Class ilCmiXapiUser
  *
@@ -123,7 +126,6 @@ public static function getIliasUuid(): ?string
         $setting = new ilSetting('cmix');
         // Fallback
         if (null == $setting->get('ilias_uuid', null)) {
-            // $uuid = (new \Ramsey\Uuid\UuidFactory())->uuid4()->toString();
             $uuid = self::getUUID(32);
             $setting->set('ilias_uuid', $uuid);
         }
@@ -583,24 +585,24 @@ private static function userObjectUniqueIdExists(string $id): bool
         return $result->numRows() != 0;
     }
 
-    public static function generateCMI5Registration(int $objId, int $usrId): \Ramsey\Uuid\UuidInterface
+    public static function generateCMI5Registration(int $objId, int $usrId): Uuid
     {
-        return (new \Ramsey\Uuid\UuidFactory())->uuid3(self::getIliasUuid(), $objId . '-' . $usrId);
+        return (new UuidFactory())->uuid3(self::getIliasUuid(), $objId . '-' . $usrId);
     }
 
-    public static function generateRegistration(ilObjCmiXapi $obj, ilObjUser $user): \Ramsey\Uuid\UuidInterface
+    public static function generateRegistration(ilObjCmiXapi $obj, ilObjUser $user): Uuid
     {
-        return (new \Ramsey\Uuid\UuidFactory())->uuid3(self::getIliasUuid(), $obj->getRefId() . '-' . $user->getId());
+        return (new UuidFactory())->uuid3(self::getIliasUuid(), $obj->getRefId() . '-' . $user->getId());
     }
 
-    public static function getCMI5RegistrationFromAuthToken(ilCmiXapiAuthToken $authToken): \Ramsey\Uuid\UuidInterface
+    public static function getCMI5RegistrationFromAuthToken(ilCmiXapiAuthToken $authToken): Uuid
     {
-        return (new \Ramsey\Uuid\UuidFactory())->uuid3(self::getIliasUuid(), $authToken->getObjId() . '-' . $authToken->getUsrId());
+        return (new UuidFactory())->uuid3(self::getIliasUuid(), $authToken->getObjId() . '-' . $authToken->getUsrId());
     }
 
-    public static function getRegistrationFromAuthToken(ilCmiXapiAuthToken $authToken): \Ramsey\Uuid\UuidInterface
+    public static function getRegistrationFromAuthToken(ilCmiXapiAuthToken $authToken): Uuid
     {
-        return (new \Ramsey\Uuid\UuidFactory())->uuid3(self::getIliasUuid(), $authToken->getRefId() . '-' . $authToken->getUsrId());
+        return (new UuidFactory())->uuid3(self::getIliasUuid(), $authToken->getRefId() . '-' . $authToken->getUsrId());
     }
 
     public static function getUsrIdForObjectAndUsrIdent(int $objId, string $userIdent): ?int
diff --git a/components/ILIAS/Data/src/UUID/Factory.php b/components/ILIAS/Data/src/UUID/Factory.php
index 8b037ca7d60b..bcd85c2778a0 100755
--- a/components/ILIAS/Data/src/UUID/Factory.php
+++ b/components/ILIAS/Data/src/UUID/Factory.php
@@ -48,6 +48,23 @@ public function uuid4AsString(): string
         return $this->uuid4()->toString();
     }
 
+    /**
+     * Name-based UUID (version 3, MD5): the same namespace and name always result in the same UUID.
+     *
+     * @param Uuid|string $namespace a UUID, with or without hyphens
+     */
+    public function uuid3(Uuid|string $namespace, string $name): Uuid
+    {
+        return new RamseyUuidWrapper(
+            $this->uuid_factory->uuid3($namespace instanceof Uuid ? $namespace->toString() : $namespace, $name)
+        );
+    }
+
+    public function uuid3AsString(Uuid|string $namespace, string $name): string
+    {
+        return $this->uuid3($namespace, $name)->toString();
+    }
+
     public function fromString(string $uuid): Uuid
     {
         return new RamseyUuidWrapper($this->uuid_factory->fromString($uuid));
diff --git a/components/ILIAS/Data/tests/UuidTest.php b/components/ILIAS/Data/tests/UuidTest.php
index f1eea3b7bd8b..01a2813a32b0 100755
--- a/components/ILIAS/Data/tests/UuidTest.php
+++ b/components/ILIAS/Data/tests/UuidTest.php
@@ -57,6 +57,30 @@ public function test_uuid4_string(): void
         $this->assertMatchesRegularExpression(self::VALID_UUID4, $uuid);
     }
 
+    /**
+     * Name-based UUIDs must never change: they are stored and compared, e.g. as cmi5 registrations.
+     * Expected values cross-checked with Python's uuid.uuid3().
+     */
+    #[\PHPUnit\Framework\Attributes\Depends('test_init')]
+    public function test_uuid3_is_stable(): void
+    {
+        $factory = new Factory();
+
+        $this->assertSame(
+            'cdefba47-4fc6-3904-99e9-989195f87f2c',
+            $factory->uuid3AsString('6ba7b810-9dad-11d1-80b4-00c04fd430c8', 'www.ilias.de')
+        );
+        // namespace without hyphens, as stored by CmiXapi
+        $this->assertSame(
+            'd60304bc-9cb8-3988-9fa1-e6953cc506e7',
+            $factory->uuid3AsString('0123456789abcdef0123456789abcdef', '12-34')
+        );
+        $this->assertSame(
+            'cdefba47-4fc6-3904-99e9-989195f87f2c',
+            $factory->uuid3($factory->fromString('6ba7b810-9dad-11d1-80b4-00c04fd430c8'), 'www.ilias.de')->toString()
+        );
+    }
+
     #[\PHPUnit\Framework\Attributes\Depends('test_init')]
     public function test_from_string(): void
     {