diff --git a/src/Messages/TSMessagesManager.m b/src/Messages/TSMessagesManager.m
index 4e302e7c2..8abee3b8a 100644
--- a/src/Messages/TSMessagesManager.m
+++ b/src/Messages/TSMessagesManager.m
@@ -271,6 +271,14 @@ NS_ASSUME_NONNULL_BEGIN
                 return;
             }
 
+            NSUInteger kMaxEncryptedDataLength = 250 * 1024;
+            if (encryptedData.length > kMaxEncryptedDataLength) {
+                DDLogError(@"Skipping message envelope with oversize encrypted data: %lu.",
+                    (unsigned long)encryptedData.length);
+                completion(nil);
+                return;
+            }
+
             NSData *plaintextData;
 
             @try {