Vulnerability Monitor

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CVE-2023-51766

Exim before 4.97.1 allows SMTP smuggling in certain PIPELINING/CHUNKING 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 Exim supports <LF>.<CR><LF> but some other popular e-mail servers do not.

Published

2023-12-24T06:15:07.673

Last Modified

2025-11-04T19:16:21.973

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	exim	exim	< 4.97.1	Yes
Application	fedoraproject	extra_packages_for_enterprise_linux	7.0	Yes
Application	fedoraproject	extra_packages_for_enterprise_linux	8.0	Yes
Application	fedoraproject	extra_packages_for_enterprise_linux	9.0	Yes
Operating System	fedoraproject	fedora	38	Yes
Operating System	fedoraproject	fedora	39	Yes
Operating System	debian	debian_linux	10.0	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/2023/12/29/2 Mailing List, Mitigation, Third Party Advisory ([email protected])
http://www.openwall.com/lists/oss-security/2024/01/01/1 Mailing List, Third Party Advisory ([email protected])
http://www.openwall.com/lists/oss-security/2024/01/01/2 Mailing List, Third Party Advisory ([email protected])
http://www.openwall.com/lists/oss-security/2024/01/01/3 Mailing List, Third Party Advisory ([email protected])
https://bugs.exim.org/show_bug.cgi?id=3063 Issue Tracking, Vendor Advisory ([email protected])
https://bugzilla.redhat.com/show_bug.cgi?id=2255852 Issue Tracking, Third Party Advisory ([email protected])
https://exim.org/static/doc/security/CVE-2023-51766.txt Broken Link ([email protected])
https://fahrplan.events.ccc.de/congress/2023/fahrplan/events/11782.html Technical Description ([email protected])
https://git.exim.org/exim.git/commit/5bb786d5ad568a88d50d15452aacc8404047e5ca Patch ([email protected])
https://git.exim.org/exim.git/commit/cf1376206284f2a4f11e32d931d4aade34c206c5 Patch ([email protected])
https://github.com/Exim/exim/blob/master/doc/doc-txt/cve-2023-51766 Mitigation, Vendor Advisory ([email protected])
https://lists.debian.org/debian-lts-announce/2024/01/msg00002.html Mailing List, Third Party Advisory ([email protected])
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ORN7OKEQPPBKUHYRQ6LR5PSNBQVDHAWB/ Mailing List, Third Party Advisory ([email protected])
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QPDWHJPABVJCXDSNELSSVTIVAJU2MDUQ/ Mailing List, Third Party Advisory ([email protected])
https://lwn.net/Articles/956533/ Third Party Advisory ([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/2023/12/23/2 Issue Tracking, 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/2023/12/29/2 Mailing List, Mitigation, Third Party Advisory (af854a3a-2127-422b-91ae-364da2661108)
http://www.openwall.com/lists/oss-security/2024/01/01/1 Mailing List, Third Party Advisory (af854a3a-2127-422b-91ae-364da2661108)
http://www.openwall.com/lists/oss-security/2024/01/01/2 Mailing List, Third Party Advisory (af854a3a-2127-422b-91ae-364da2661108)
http://www.openwall.com/lists/oss-security/2024/01/01/3 Mailing List, Third Party Advisory (af854a3a-2127-422b-91ae-364da2661108)
https://bugs.exim.org/show_bug.cgi?id=3063 Issue Tracking, Vendor Advisory (af854a3a-2127-422b-91ae-364da2661108)
https://bugzilla.redhat.com/show_bug.cgi?id=2255852 Issue Tracking, Third Party Advisory (af854a3a-2127-422b-91ae-364da2661108)
https://exim.org/static/doc/security/CVE-2023-51766.txt Broken Link (af854a3a-2127-422b-91ae-364da2661108)
https://fahrplan.events.ccc.de/congress/2023/fahrplan/events/11782.html Technical Description (af854a3a-2127-422b-91ae-364da2661108)
https://git.exim.org/exim.git/commit/5bb786d5ad568a88d50d15452aacc8404047e5ca Patch (af854a3a-2127-422b-91ae-364da2661108)
https://git.exim.org/exim.git/commit/cf1376206284f2a4f11e32d931d4aade34c206c5 Patch (af854a3a-2127-422b-91ae-364da2661108)
https://github.com/Exim/exim/blob/master/doc/doc-txt/cve-2023-51766 Mitigation, Vendor Advisory (af854a3a-2127-422b-91ae-364da2661108)
https://lists.debian.org/debian-lts-announce/2024/01/msg00002.html Mailing List, Third Party Advisory (af854a3a-2127-422b-91ae-364da2661108)
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ORN7OKEQPPBKUHYRQ6LR5PSNBQVDHAWB/ Mailing List, Third Party Advisory (af854a3a-2127-422b-91ae-364da2661108)
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QPDWHJPABVJCXDSNELSSVTIVAJU2MDUQ/ Mailing List, Third Party Advisory (af854a3a-2127-422b-91ae-364da2661108)
https://lists.fedoraproject.org/archives/list/[email protected]/message/ORN7OKEQPPBKUHYRQ6LR5PSNBQVDHAWB/ (af854a3a-2127-422b-91ae-364da2661108)
https://lists.fedoraproject.org/archives/list/[email protected]/message/QPDWHJPABVJCXDSNELSSVTIVAJU2MDUQ/ (af854a3a-2127-422b-91ae-364da2661108)
https://lwn.net/Articles/956533/ Third Party Advisory (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/2023/12/23/2 Issue Tracking, Mailing List, Third Party Advisory (af854a3a-2127-422b-91ae-364da2661108)
https://www.youtube.com/watch?v=V8KPV96g1To Exploit (af854a3a-2127-422b-91ae-364da2661108)