Best Practical Request Tracker (RT) before 4.4.7 and 5.x before 5.0.5 allows Information Disclosure via fake or spoofed RT email headers in an email message or a mail-gateway REST API call.
https://lists.debian.org/debian-lts-announce/2023/10/msg00046.html
https://docs.bestpractical.com/release-notes/rt/index.html