CVE-2023-51765
sendmail through at least 8.14.7 allows SMTP smuggling in certain configurations. Remote...
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- Low
- Availability
- None
Exploit likelihood
What each source reports
NVD Score used
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.
- Record
CVE-2023-51765- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N - Weakness
- CWE-345
- Updated
- 2026-11-02
CVE List No score
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.
- Record
CVE-2023-51765- Updated
- 2026-11-02
EUVDEUVD-2023-56454 No score
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.
- Record
EUVD-2023-56454- Updated
- 2026-11-03
GitHub AdvisoriesGHSA-5rcq-25vc-g8qr
sendmail through at least 8.14.7 allows SMTP smuggling in certain configurations. Remote...
sendmail through at least 8.14.7 allows SMTP smuggling in certain configurations. Remote attackers can use a published exploitation technique to inject e-mail messages that appear to originate from the sendmail server, allowing bypass of an SPF protection mechanism. This occurs because sendmail supports <LF>.<CR><LF> but some other popular e-mail servers do not.
- Record
GHSA-5rcq-25vc-g8qr- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N - Weakness
- CWE-345
- Updated
- 2026-11-02
OSVAZL-32295
CVE-2023-51765 affecting package sendmail 8.15.2-46
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.
- Record
AZL-32295- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N - Updated
- 2026-11-02
OSVDEBIAN-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.
- Record
DEBIAN-CVE-2023-51765- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N - Updated
- 2026-11-02
Show 6 moreShow less
OSVUBUNTU-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.
- Record
UBUNTU-CVE-2023-51765- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N - Updated
- 2026-11-02
OSV No score
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.
- Record
CVE-2023-51765- Updated
- 2026-11-02
OSVMGASA-2024-0270 No score
Updated sendmail packages fix security vulnerability
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. (CVE-2023-51765)
- Record
MGASA-2024-0270- Updated
- 2026-11-02
OSVopenSUSE-SU-2024:13658-1 No score
libmilter-doc-8.18.1-1.1 on GA media
These are all security issues fixed in the libmilter-doc-8.18.1-1.1 package on the GA media of openSUSE Tumbleweed.
- Record
openSUSE-SU-2024:13658-1- Updated
- 2026-11-02
OSVSUSE-SU-2024:0742-1 No score
Security update for sendmail
This update for sendmail fixes the following issues:
- CVE-2023-51765: Fixed new SMTP smuggling attack. (bsc#1218351)
- Record
SUSE-SU-2024:0742-1- Updated
- 2026-11-02
OSVSUSE-SU-2024:0743-1 No score
Security update for sendmail
This update for sendmail fixes the following issues:
- CVE-2023-51765: Fixed new SMTP smuggling attack. (bsc#1218351)
- Record
SUSE-SU-2024:0743-1- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
sendmailAzure Linux:2 |
through 8.15.2-46 | None known |
sendmailDebian:12 |
before 8.17.1.9-2+deb12u1, plus listed versions 8.17.1.9-2 |
8.17.1.9-2+deb12u1 |
sendmailDebian:13 |
before 8.18.1-1 | 8.18.1-1 |
sendmailDebian:14 |
before 8.18.1-1 | 8.18.1-1 |
sendmailDebian:10 |
before 8.15.2-14~deb10u2, plus listed versions 8.15.2-128.15.2-138.15.2-14~deb10u1 |
8.15.2-14~deb10u2 |
sendmailMageia:9 |
before 8.17.1-4.1.mga9 | 8.17.1-4.1.mga9 |
sendmailSUSE:Linux Enterprise Module for Legacy 12 |
before 8.14.9-4.9.1 | 8.14.9-4.9.1 |
sendmailSUSE:Linux Enterprise Module for Basesystem 15 SP5 |
before 8.15.2-150000.8.12.1 | 8.15.2-150000.8.12.1 |
sendmailSUSE:Linux Enterprise Module for Package Hub 15 SP5 |
before 8.15.2-150000.8.12.1 | 8.15.2-150000.8.12.1 |
sendmailopenSUSE:Leap 15.5 |
before 8.15.2-150000.8.12.1 | 8.15.2-150000.8.12.1 |
Show 5 moreShow less
| Package | Affected | Fixed |
|---|---|---|
sendmailUbuntu:14.04:LTS |
All versions, plus listed versions 8.14.4-2.1ubuntu48.14.4-2.1ubuntu58.14.4-4.1ubuntu18.14.4-4.1ubuntu1.1 |
None known |
sendmailUbuntu:16.04:LTS |
All versions, plus listed versions 8.14.9-48.15.2-28.15.2-3 |
None known |
sendmailUbuntu:18.04:LTS |
All versions, plus listed versions 8.15.2-8ubuntu18.15.2-9ubuntu18.15.2-10 |
None known |
sendmailUbuntu:20.04:LTS |
All versions, plus listed versions 8.15.2-138.15.2-17ubuntu18.15.2-18 |
None known |
sendmailUbuntu:22.04:LTS |
All versions, plus listed versions 8.15.2-22ubuntu28.15.2-22ubuntu3 |
None known |
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2023-51765 is a medium vulnerability (CVSS 5.3) in Sendmail, published December 24, 2023. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.08%, the 65th percentile. Fixed in sendmail 8.17.1.9-2+deb12u1.
References
sec-consult.com/blog/detail/smtp-smuggling-spoofing-e-mails-worldwide
openwall.com/lists/oss-security/2023/12/22/7
github.com/freebsd/freebsd-src/commit/5dd76dd0cc19450133aa379ce0ce4a68ae07fb39
Show 24 moreShow less
bugzilla.suse.com/show_bug.cgi?id=1218351
bugzilla.redhat.com/show_bug.cgi?id=2255869
access.redhat.com/security/cve/CVE-2023-51765
fahrplan.events.ccc.de/congress/2023/fahrplan/events/11782.html
youtube.com/watch?v=V8KPV96g1To
lwn.net/Articles/956533
lists.debian.org/debian-lts-announce/2024/06/msg00004.html
nvd.nist.gov/vuln/detail/CVE-2023-51765
security-tracker.debian.org/tracker/CVE-2023-51765
advisories.mageia.org/MGASA-2024-0270.html
bugs.mageia.org/show_bug.cgi?id=32700
suse.com/support/update/announcement/2024/suse-su-20240742-1
ubuntu.com/security/CVE-2023-51765
cve.org/CVERecord?id=CVE-2023-51765