CVE-2023-51765
First published: Sun Dec 24 2023(Updated: )
escription: By exploiting interpretation differences of the SMTP protocol, it is possible to smuggle/send spoofed e-mails - hence SMTP smuggling - while still passing SPF alignment checks. During this research, two types of SMTP smuggling, outbound and inbound, were discovered. These allowed sending spoofed e-mails from millions of domains (e.g., admin[@]outlook.com) to millions of receiving SMTP servers (e.g., Amazon, PayPal, eBay). Identified vulnerabilities in Microsoft and GMX were quickly fixed, however, SEC Consult urges companies using the also affected Cisco Secure Email product to manually update their vulnerable default configuration. References: <a href="https://sec-consult.com/blog/detail/smtp-smuggling-spoofing-e-mails-worldwide/">https://sec-consult.com/blog/detail/smtp-smuggling-spoofing-e-mails-worldwide/</a>
Credit: cve@mitre.org
| Affected Software | Affected Version | How to fix |
|---|---|---|
| redhat/sendmail | <8.18.0.2 | 8.18.0.2 |
| Sendmail | <8.18.0.2 | |
| FreeBSD Kernel | <11.0 | |
| Red Hat Enterprise Linux | =8.0 | |
| Red Hat Enterprise Linux | =9.0 |
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Reference Links
- https://sec-consult.com/blog/detail/smtp-smuggling-spoofing-e-mails-worldwide/
- https://bugzilla.redhat.com/show_bug.cgi/show_bug.cgi?id=2255870
- https://bugzilla.redhat.com/show_bug.cgi?id=2255869
- http://www.openwall.com/lists/oss-security/2023/12/24/1
- http://www.openwall.com/lists/oss-security/2023/12/25/1
- http://www.openwall.com/lists/oss-security/2023/12/26/5
- http://www.openwall.com/lists/oss-security/2023/12/29/5
- http://www.openwall.com/lists/oss-security/2023/12/30/1
- http://www.openwall.com/lists/oss-security/2023/12/30/3
- https://access.redhat.com/security/cve/CVE-2023-51765
- https://bugzilla.suse.com/show_bug.cgi?id=1218351
- https://fahrplan.events.ccc.de/congress/2023/fahrplan/events/11782.html
- https://github.com/freebsd/freebsd-src/commit/5dd76dd0cc19450133aa379ce0ce4a68ae07fb39#diff-afdf514b32ac88004952c11660c57bc96c3d8b2234007c1cbd8d7ed7fd7935cc
- https://lwn.net/Articles/956533/
- https://www.openwall.com/lists/oss-security/2023/12/21/7
- https://www.openwall.com/lists/oss-security/2023/12/22/7
- https://www.youtube.com/watch?v=V8KPV96g1To
- https://lists.debian.org/debian-lts-announce/2024/06/msg00004.html
Frequently Asked Questions
What is the severity of CVE-2023-51765?
CVE-2023-51765 has a critical severity due to its potential for SMTP smuggling and spoofing of emails.
How do I fix CVE-2023-51765?
To fix CVE-2023-51765, upgrade your Sendmail version to 8.18.0.2 or higher.
Which software is affected by CVE-2023-51765?
CVE-2023-51765 affects Sendmail versions below 8.18.0.2 and various versions of Red Hat Enterprise Linux.
Can CVE-2023-51765 be exploited remotely?
Yes, CVE-2023-51765 can be exploited remotely through manipulation of the SMTP protocol.
What type of attacks can CVE-2023-51765 enable?
CVE-2023-51765 can enable both outbound and inbound SMTP smuggling attacks.
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