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AWS cognito medium security documentation change

Service: cognito · 2026-06-25 · Security-related medium

File: cognito/latest/developerguide/user-pool-settings-attributes.md

Summary

Added security note about 'sub' attribute format validation

Security assessment

Addresses potential security issues by explicitly warning against strict validation of 'sub' attribute format

Diff

diff --git a/cognito/latest/developerguide/user-pool-settings-attributes.md b/cognito/latest/developerguide/user-pool-settings-attributes.md
index 4f2af4ed0..38017c1cd 100644
--- a//cognito/latest/developerguide/user-pool-settings-attributes.md
+++ b//cognito/latest/developerguide/user-pool-settings-attributes.md
@@ -127,0 +128,4 @@ Index and search your users based on the `sub` attribute. The `sub` attribute is
+###### Important
+
+Amazon Cognito generates `sub` in an Amazon Cognito-specific format that doesn't conform to a specific UUID format, including RFC UUID. You shouldn't strictly validate the format of `sub`.
+