BIT-discourse-2026-53961: Discourse: Forged AWS SNS bounce notifications can disable a targeted user's email (missing TopicArn binding)

Discourse versions prior to 2026.6.0, 2026.5.1, 2026.4.2, and 2026.1.5 contain a vulnerability in the AWS SES bounce webhook. The webhook verified that SNS messages were signed by Amazon but did not…