Zendesk before 2024-07-02 allows remote attackers to read ticket history via e-mail spoofing, because Cc fields are extracted from incoming e-mail messages and used to grant additional authorization for ticket viewing, the mechanism for detecting spoofed e-mail messages is insufficient, and the support e-mail addresses associated with individual tickets are predictable.
https://x.com/hackermondev/status/1844877950698537323
https://news.ycombinator.com/item?id=41818459
https://gist.github.com/hackermondev/68ec8ed145fcee49d2f5e2b9d2cf2e52