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AWS cognito documentation change

Service: cognito · 2025-07-25 · Documentation medium

File: cognito/latest/developerguide/cognito-user-pools-working-with-lambda-triggers.md

Summary

Added clarification about unmodified Lambda trigger events and default behavior

Security assessment

The change clarifies Lambda trigger behavior, which helps developers implement secure workflows. However, it does not address a specific security vulnerability.

Diff

diff --git a/cognito/latest/developerguide/cognito-user-pools-working-with-lambda-triggers.md b/cognito/latest/developerguide/cognito-user-pools-working-with-lambda-triggers.md
index 161590edb..c4ada8790 100644
--- a//cognito/latest/developerguide/cognito-user-pools-working-with-lambda-triggers.md
+++ b//cognito/latest/developerguide/cognito-user-pools-working-with-lambda-triggers.md
@@ -15 +15 @@ Lambda triggers can customize the response that Amazon Cognito delivers to your
-When you have a Lambda trigger assigned to your user pool, Amazon Cognito interrupts its default flow to request information from your function. Amazon Cognito generates a JSON _event_ and passes it to your function. The event contains information about your user's request to create a user account, sign in, reset a password, or update an attribute. Your function then has an opportunity to take action, or to send the event back unmodified.
+When you have a Lambda trigger assigned to your user pool, Amazon Cognito interrupts its default flow to request information from your function. Amazon Cognito generates a JSON _event_ and passes it to your function. The event contains information about your user's request to create a user account, sign in, reset a password, or update an attribute. Your function then has an opportunity to take action, or to send the event back unmodified. An event returned unmodified notifies your user pool to proceed with the default action for the event. For example, your pre sign-up trigger can automatically confirm users for the `PreSignUp_SignUp` trigger source, but return the event unchanged for external and administrator-created users.
@@ -98,0 +99,6 @@ The following example Lambda resource-based policy grants Amazon Cognito a limit
+JSON
+    
+
+****
+    
+