Vulnerability Monitor

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CVE-2023-51765

sendmail through 8.17.2 allows SMTP smuggling in certain configurations. Remote attackers can use a published exploitation technique to inject e-mail messages with a spoofed MAIL FROM address, allowing bypass of an SPF protection mechanism. This occurs because sendmail supports <LF>.<CR><LF> but some other popular e-mail servers do not. This is resolved in 8.18 and later versions with 'o' in srv_features.

Security Impact Summary

This vulnerability carries a MEDIUM severity rating with a CVSS v3.1 score of 5.3, indicating it can be exploited remotely over the network with relatively low complexity without requiring user interaction and does not require pre-existing privileges . The vulnerability impacts limited integrity, for affected systems. Impacting 3 products from sendmail, from freebsd, from redhat organizations running these solutions should prioritize assessment and patching.

Historical Context

Reported in 2023, this vulnerability emerged during an era marked by increased sophistication in supply chain attacks, cloud infrastructure vulnerabilities, and software-as-a-service (SaaS) security challenges. Security practices during this period emphasized zero-trust architectures, container security, and API protection.

Published

2023-12-24T06:15:07.527

Last Modified

2024-11-21T08:38:44.980

Status

Modified

Source

[email protected]

Severity

CVSSv3.1: 5.3 (MEDIUM)

Weaknesses

Type: Primary
CWE-345

Affected Vendors & Products

Type	Vendor	Product	Version/Range	Vulnerable?
Application	sendmail	sendmail	< 8.18.0.2	Yes
Operating System	freebsd	freebsd	< 11.0	Yes
Operating System	redhat	enterprise_linux	8.0	Yes
Operating System	redhat	enterprise_linux	9.0	Yes

References

http://www.openwall.com/lists/oss-security/2023/12/24/1 Mailing List, Third Party Advisory ([email protected])
http://www.openwall.com/lists/oss-security/2023/12/25/1 Mailing List, Third Party Advisory ([email protected])
http://www.openwall.com/lists/oss-security/2023/12/26/5 Mailing List, Third Party Advisory ([email protected])
http://www.openwall.com/lists/oss-security/2023/12/29/5 Mailing List, Third Party Advisory ([email protected])
http://www.openwall.com/lists/oss-security/2023/12/30/1 Mailing List, Third Party Advisory ([email protected])
http://www.openwall.com/lists/oss-security/2023/12/30/3 Mailing List, Third Party Advisory ([email protected])
https://access.redhat.com/security/cve/CVE-2023-51765 Third Party Advisory ([email protected])
https://bugzilla.redhat.com/show_bug.cgi?id=2255869 Issue Tracking, Third Party Advisory ([email protected])
https://bugzilla.suse.com/show_bug.cgi?id=1218351 Issue Tracking, Patch, Third Party Advisory ([email protected])
https://fahrplan.events.ccc.de/congress/2023/fahrplan/events/11782.html Technical Description ([email protected])
https://github.com/freebsd/freebsd-src/commit/5dd76dd0cc19450133aa379ce0ce4a68ae07fb39#diff-afdf514b32ac88004952c11660c57bc96c3d8b2234007c1cbd8d7ed7fd7935cc Patch ([email protected])
https://lists.debian.org/debian-lts-announce/2024/06/msg00004.html ([email protected])
https://lwn.net/Articles/956533/ ([email protected])
https://sec-consult.com/blog/detail/smtp-smuggling-spoofing-e-mails-worldwide/ Technical Description, Third Party Advisory ([email protected])
https://www.openwall.com/lists/oss-security/2023/12/21/7 Mailing List, Third Party Advisory ([email protected])
https://www.openwall.com/lists/oss-security/2023/12/22/7 Mailing List, Third Party Advisory ([email protected])
https://www.youtube.com/watch?v=V8KPV96g1To Exploit ([email protected])
http://www.openwall.com/lists/oss-security/2023/12/24/1 Mailing List, Third Party Advisory (af854a3a-2127-422b-91ae-364da2661108)
http://www.openwall.com/lists/oss-security/2023/12/25/1 Mailing List, Third Party Advisory (af854a3a-2127-422b-91ae-364da2661108)
http://www.openwall.com/lists/oss-security/2023/12/26/5 Mailing List, Third Party Advisory (af854a3a-2127-422b-91ae-364da2661108)
http://www.openwall.com/lists/oss-security/2023/12/29/5 Mailing List, Third Party Advisory (af854a3a-2127-422b-91ae-364da2661108)
http://www.openwall.com/lists/oss-security/2023/12/30/1 Mailing List, Third Party Advisory (af854a3a-2127-422b-91ae-364da2661108)
http://www.openwall.com/lists/oss-security/2023/12/30/3 Mailing List, Third Party Advisory (af854a3a-2127-422b-91ae-364da2661108)
https://access.redhat.com/security/cve/CVE-2023-51765 Third Party Advisory (af854a3a-2127-422b-91ae-364da2661108)
https://bugzilla.redhat.com/show_bug.cgi?id=2255869 Issue Tracking, Third Party Advisory (af854a3a-2127-422b-91ae-364da2661108)
https://bugzilla.suse.com/show_bug.cgi?id=1218351 Issue Tracking, Patch, Third Party Advisory (af854a3a-2127-422b-91ae-364da2661108)
https://fahrplan.events.ccc.de/congress/2023/fahrplan/events/11782.html Technical Description (af854a3a-2127-422b-91ae-364da2661108)
https://github.com/freebsd/freebsd-src/commit/5dd76dd0cc19450133aa379ce0ce4a68ae07fb39#diff-afdf514b32ac88004952c11660c57bc96c3d8b2234007c1cbd8d7ed7fd7935cc Patch (af854a3a-2127-422b-91ae-364da2661108)
https://lists.debian.org/debian-lts-announce/2024/06/msg00004.html (af854a3a-2127-422b-91ae-364da2661108)
https://lwn.net/Articles/956533/ (af854a3a-2127-422b-91ae-364da2661108)
https://sec-consult.com/blog/detail/smtp-smuggling-spoofing-e-mails-worldwide/ Technical Description, Third Party Advisory (af854a3a-2127-422b-91ae-364da2661108)
https://www.openwall.com/lists/oss-security/2023/12/21/7 Mailing List, Third Party Advisory (af854a3a-2127-422b-91ae-364da2661108)
https://www.openwall.com/lists/oss-security/2023/12/22/7 Mailing List, Third Party Advisory (af854a3a-2127-422b-91ae-364da2661108)
https://www.youtube.com/watch?v=V8KPV96g1To Exploit (af854a3a-2127-422b-91ae-364da2661108)

How SecUtils Interprets This CVE

SecUtils normalizes and enriches National Vulnerability Database (NVD) records by standardizing vendor and product identifiers, aggregating vulnerability metadata from both NVD and MITRE sources, and providing structured context for security teams. For sendmail's affected products, we extract Common Platform Enumeration (CPE) data, Common Weakness Enumeration (CWE) classifications, CVSS severity metrics, and reference data to enable rapid vulnerability prioritization and asset correlation. This record contains no exploit code, proof-of-concept instructions, or attack methodologies—only defensive intelligence necessary for patch management, risk assessment, and security operations.