SMTP Smuggling Vulnerability in Postfix Email Server
CVE-2023-51764

5.3MEDIUM

Key Information:

Vendor

Postfix

Status
Postfix
Vendor
CVE Published:
24 December 2023

Badges

👾 Exploit Exists🟡 Public PoC🟣 EPSS 27%

What is CVE-2023-51764?

An SMTP smuggling vulnerability exists in Postfix through version 3.8.5, allowing remote attackers to exploit improperly configured servers to inject spoofed email messages. This occurs due to the way Postfix handles line feed characters (.), which some other email servers may not recognize. Without proper configuration, such as setting smtpd_data_restrictions to reject_unauth_pipelining and leveraging other configurations, SPF protections can be bypassed. To mitigate these risks, administrators should ensure they are using a Postfix version of at least 3.5.23, 3.6.13, 3.7.9, or 3.8.4, and implement the smtpd_forbid_bare_newline option.

Exploit Proof of Concept (PoC)

PoC code is written by security researchers to demonstrate the vulnerability can be exploited. PoC code is also a key component for weaponization which could lead to ransomware.

CVE-2023-51764
Created by duy-31

CVE-2023-51764
Created by eeenvik1

CVE-2023-51764-POC
Created by d4op

References

https://www.postfix.org/smtp-smuggling.html
https://sec-consult.com/blog/detail/smtp-smuggling-spoofi...
http://www.openwall.com/lists/oss-security/2023/12/24/1
mailing-list

EPSS Score

27% chance of being exploited in the next 30 days.

CVSS V3.1

Score:
5.3
Severity:
MEDIUM
Confidentiality:
None
Integrity:
Low
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • 🟡

    Public PoC available

  • 👾

    Exploit known to exist

  • Vulnerability published

  • Vulnerability Reserved

.