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aws AWS What's New ·

AWS STS Simplifies Session Token Limits and Adds Monitoring

securityawsgaengineeraws-iam
feature

AWS Security Token Service (STS) now enforces a unified 4,096-byte size limit for session tokens, streamlining previous separate limits for token size and parameters such as inline policies, managed policies, and session tags. This change offers increased flexibility for complex combinations of session policies and tags. Additionally, STS introduces new monitoring capabilities, returning session token size and utilization in response elements, which are logged in CloudTrail and published as metrics in CloudWatch. An optional API parameter is also available for generating larger session tokens to test application compatibility.

  • →Session Token Size Monitoring and Testing
  • →Unified Session Token Size Limit
Features (1) ›
  • Session Token Size Monitoring and Testing

    STS now returns response elements indicating session token size and percentage utilization relative to the limit, logging these values in AWS CloudTrail and publishing corresponding metrics in Amazon CloudWatch. An optional API parameter also allows generating larger session tokens, up to the 4,096-byte limit, to test application and infrastructure compatibility.

Enhancements (1) ›
  • Unified Session Token Size Limit

    AWS STS now enforces a single 4,096-byte size limit on session tokens, consolidating previous separate limits for session token size and passed-in parameters like inline policies, managed policies, and session tags. This provides more flexibility for larger combinations of session policies and session tags.

Read the original announcement →

https://aws.amazon.com/about-aws/whats-new/2026/09/aws-sts/

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