SMTP smuggling attack in Sendmail

1) Command Injection

EUVDB-ID: #VU84797

Risk: Medium

CVSSv3.1: 6 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N/E:U/RL:U/RC:C]

CVE-ID: CVE-2023-51765

CWE-ID: CWE-77 - Command injection

Exploit availability: No

Description

The vulnerability allows a remote attacker to spoof email messages.

The vulnerability exists due to an error when handling line endings other than <CR><LF>. A remote attacker can spoof contents of email message and bypass SPF protection mechanism.

Mitigation

Cybersecurity Help is currently unaware of any official solution to address this vulnerability.

Vulnerable software versions

Sendmail: 2.6 - 8.17.2

External links

http://sec-consult.com/blog/detail/smtp-smuggling-spoofing-e-mails-worldwide/
http://www.openwall.com/lists/oss-security/2023/12/22/7
http://www.openwall.com/lists/oss-security/2023/12/21/7
http://github.com/freebsd/freebsd-src/commit/5dd76dd0cc19450133aa379ce0ce4a68ae07fb39#diff-afdf514b32ac88004952c11660c57bc96c3d8b2234007c1cbd8d7ed7fd7935cc
http://www.openwall.com/lists/oss-security/2023/12/24/1
http://www.openwall.com/lists/oss-security/2023/12/25/1
http://bugzilla.suse.com/show_bug.cgi?id=1218351
http://bugzilla.redhat.com/show_bug.cgi?id=2255869
http://access.redhat.com/security/cve/CVE-2023-51765
http://fahrplan.events.ccc.de/congress/2023/fahrplan/events/11782.html
http://www.openwall.com/lists/oss-security/2023/12/26/5

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

How the attacker can exploit this vulnerability?

The attacker would have to send a specially crafted request to the affected application in order to exploit this vulnerability.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.