Summary

aiosmtpd is vulnerable to inbound SMTP smuggling. SMTP smuggling is a novel vulnerability based on not so novel interpretation differences of the SMTP protocol. By exploiting SMTP smuggling, an attacker may send smuggle/spoof e-mails with fake sender addresses, allowing advanced phishing attacks. This issue also existed in other SMTP software like Postfix (https://www.postfix.org/smtp-smuggling.html).

Details

Detailed information on SMTP smuggling can be found in the full blog post (https://sec-consult.com/blog/detail/smtp-smuggling-spoofing-e-mails-worldwide/) or on the Postfix homepage (https://www.postfix.org/smtp-smuggling.html). (and soon on the official website https://smtpsmuggling.com/)

Impact

With the right SMTP server constellation, an attacker can send spoofed e-mails to inbound/receiving aiosmtpd instances.

References

• GHSA-pr2m-px7j-xg65
• https://nvd.nist.gov/vuln/detail/CVE-2024-27305
• aio-libs/aiosmtpd@24b6c79
• https://www.postfix.org/smtp-smuggling.html