CVE-2023-51765

MEDIUM 5.3CVE-2023-51765 · Published 24/12/2023 · updated 17/06/2026

Package	Affected versions	Patched versions
sendmail sendmail	`< 8.18.0.2`	`8.18.0.2`

Description

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.

References

openwall.com/lists/oss-security/2023/12/24/1 · Mailing List
openwall.com/lists/oss-security/2023/12/25/1 · Mailing List
openwall.com/lists/oss-security/2023/12/26/5 · Mailing List
openwall.com/lists/oss-security/2023/12/29/5 · Mailing List
openwall.com/lists/oss-security/2023/12/30/1 · Mailing List
openwall.com/lists/oss-security/2023/12/30/3 · Mailing List
access.redhat.com/security/cve/CVE-2023-51765 · Third Party Advisory
bugzilla.redhat.com/show_bug.cgi · Issue Tracking
bugzilla.suse.com/show_bug.cgi · Issue Tracking
fahrplan.events.ccc.de/congress/2023/fahrplan/events/11782.html · Technical Description
freebsd/freebsd-src commit 5dd76dd · Patch
lists.debian.org/debian-lts-announce/2024/06/msg00004.html
lwn.net/Articles/956533
sec-consult.com/blog/detail/smtp-smuggling-spoofing-e-mails-worldwide · Technical Description
openwall.com/lists/oss-security/2023/12/21/7 · Mailing List
openwall.com/lists/oss-security/2023/12/22/7 · Mailing List
youtube.com/watch · Exploit

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