diff --git a/lib/private/TaskProcessing/Manager.php b/lib/private/TaskProcessing/Manager.php
index 4d0acc2022c..7a39d8c883b 100644
--- a/lib/private/TaskProcessing/Manager.php
+++ b/lib/private/TaskProcessing/Manager.php
@@ -938,7 +938,13 @@ class Manager implements IManager {
 		if ($this->availableTaskTypes === null) {
 			$cachedValue = $this->distributedCache->get($cacheKey);
 			if ($cachedValue !== null) {
-				$this->availableTaskTypes = unserialize($cachedValue);
+				$this->availableTaskTypes = unserialize($cachedValue, [
+				'allowed_classes' => [
+					ShapeDescriptor::class,
+					ShapeEnumValue::class,
+					EShapeType::class,
+				],
+			]);
 			}
 		}
 		// Either we have no cache or showDisabled is turned on, which we don't want to cache, ever.