# CSS in Emails: A Hidden Security Threat

Security researchers highlight how CSS in HTML emails can be abused for tracking and phishing. Malicious styles can hide content or trigger requests, turning inboxes into a vector for attacks. Users and email providers should be aware of these risks.

**Importance:** 3/5

## Sources

### Technology
- [Hacker News](https://portswigger.net/research/css-the-bomb-inside-your-inbox) — Sun, 09 Aug 2026 10:17:52 +0000