Release v1.5.53

[Aaronontheweb]

Summary

Release preparation for Akka.NET v1.5.53 - a security patch containing important fixes for TLS/SSL hostname validation and improved error diagnostics.

Changes

• Updated version to 1.5.53 in Directory.Build.props
• Added release notes to RELEASE_NOTES.md

Security Fixes

• #7897 - Fix TLS hostname validation bug and add configurable validation
  • Fixes critical bug where TLS clients validated against their own certificate DNS name instead of the remote server address
  • Adds new validate-certificate-hostname configuration option (defaults to false for backward compatibility)
  • Introduces type-safe validation APIs through new TlsValidationCallbacks factory class

Improvements

• #7891 - Improve TLS/SSL certificate error messages during handshake failures
  • Provides human-readable, actionable error messages for TLS/SSL certificate validation failures
  • Significantly improves developer experience when troubleshooting TLS issues

Release Information

• Version: 1.5.53
• Release Date: October 9th, 2025
• Milestone: https://github.com/akkadotnet/akka.net/milestone/136?closed=1
• Contributors: 1 (Aaron Stannard)
• Commits since 1.5.52: 2

This is a security patch release that continues the TLS/SSL improvements from v1.5.52.