CVE-2023-51766

  1. OpenCVE
  2. Vulnerabilities (CVE)
  3. 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.

5.3 /10

CVSS v3 : MEDIUM

V3 Legend

Vector :

Exploitability : 3.9 / Impact : 1.4

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact LOW

Availability Impact NONE

Scope UNCHANGED

References
Link Resource
http://www.openwall.com/lists/oss-security/2023/12/24/1 Mailing List Third Party Advisory
http://www.openwall.com/lists/oss-security/2023/12/25/1 Mailing List Third Party Advisory
http://www.openwall.com/lists/oss-security/2023/12/29/2 Mailing List Mitigation Third Party Advisory
http://www.openwall.com/lists/oss-security/2024/01/01/1 Mailing List Third Party Advisory
http://www.openwall.com/lists/oss-security/2024/01/01/2 Mailing List Third Party Advisory
http://www.openwall.com/lists/oss-security/2024/01/01/3 Mailing List Third Party Advisory
https://bugs.exim.org/show_bug.cgi?id=3063 Issue Tracking Vendor Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2255852 Issue Tracking Third Party Advisory
https://exim.org/static/doc/security/CVE-2023-51766.txt Broken Link
https://fahrplan.events.ccc.de/congress/2023/fahrplan/events/11782.html Technical Description
https://git.exim.org/exim.git/commit/5bb786d5ad568a88d50d15452aacc8404047e5ca Patch
https://git.exim.org/exim.git/commit/cf1376206284f2a4f11e32d931d4aade34c206c5 Patch
https://github.com/Exim/exim/blob/master/doc/doc-txt/cve-2023-51766 Mitigation Vendor Advisory
https://lists.debian.org/debian-lts-announce/2024/01/msg00002.html Mailing List Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ORN7OKEQPPBKUHYRQ6LR5PSNBQVDHAWB/ Mailing List Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QPDWHJPABVJCXDSNELSSVTIVAJU2MDUQ/ Mailing List Third Party Advisory
https://lwn.net/Articles/956533/ Third Party Advisory
https://sec-consult.com/blog/detail/smtp-smuggling-spoofing-e-mails-worldwide/ Technical Description Third Party Advisory
https://www.openwall.com/lists/oss-security/2023/12/23/2 Issue Tracking Mailing List Third Party Advisory
https://www.youtube.com/watch?v=V8KPV96g1To Exploit
http://www.openwall.com/lists/oss-security/2023/12/24/1 Mailing List Third Party Advisory
http://www.openwall.com/lists/oss-security/2023/12/25/1 Mailing List Third Party Advisory
http://www.openwall.com/lists/oss-security/2023/12/29/2 Mailing List Mitigation Third Party Advisory
http://www.openwall.com/lists/oss-security/2024/01/01/1 Mailing List Third Party Advisory
http://www.openwall.com/lists/oss-security/2024/01/01/2 Mailing List Third Party Advisory
http://www.openwall.com/lists/oss-security/2024/01/01/3 Mailing List Third Party Advisory
https://bugs.exim.org/show_bug.cgi?id=3063 Issue Tracking Vendor Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2255852 Issue Tracking Third Party Advisory
https://exim.org/static/doc/security/CVE-2023-51766.txt Broken Link
https://fahrplan.events.ccc.de/congress/2023/fahrplan/events/11782.html Technical Description
https://git.exim.org/exim.git/commit/5bb786d5ad568a88d50d15452aacc8404047e5ca Patch
https://git.exim.org/exim.git/commit/cf1376206284f2a4f11e32d931d4aade34c206c5 Patch
https://github.com/Exim/exim/blob/master/doc/doc-txt/cve-2023-51766 Mitigation Vendor Advisory
https://lists.debian.org/debian-lts-announce/2024/01/msg00002.html Mailing List Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ORN7OKEQPPBKUHYRQ6LR5PSNBQVDHAWB/ Mailing List Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QPDWHJPABVJCXDSNELSSVTIVAJU2MDUQ/ Mailing List Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/ORN7OKEQPPBKUHYRQ6LR5PSNBQVDHAWB/
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/QPDWHJPABVJCXDSNELSSVTIVAJU2MDUQ/
https://lwn.net/Articles/956533/ Third Party Advisory
https://sec-consult.com/blog/detail/smtp-smuggling-spoofing-e-mails-worldwide/ Technical Description Third Party Advisory
https://www.openwall.com/lists/oss-security/2023/12/23/2 Issue Tracking Mailing List Third Party Advisory
https://www.youtube.com/watch?v=V8KPV96g1To Exploit
Configurations

Configuration 1 (hide)

cpe:2.3:a:exim:exim:*:*:*:*:*:*:*:*

Configuration 2 (hide)

OR cpe:2.3:a:fedoraproject:extra_packages_for_enterprise_linux:7.0:*:*:*:*:*:*:*
cpe:2.3:a:fedoraproject:extra_packages_for_enterprise_linux:8.0:*:*:*:*:*:*:*
cpe:2.3:a:fedoraproject:extra_packages_for_enterprise_linux:9.0:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:38:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:39:*:*:*:*:*:*:*

Configuration 3 (hide)

cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
History

04 Nov 2025, 19:16

Type Values Removed Values Added
References
  • () https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/ORN7OKEQPPBKUHYRQ6LR5PSNBQVDHAWB/ -
  • () https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/QPDWHJPABVJCXDSNELSSVTIVAJU2MDUQ/ -
Information

Published : 2023-12-24 06:15

Updated : 2025-11-04 19:16

NVD link : CVE-2023-51766

Mitre link : CVE-2023-51766

CVE.ORG link : CVE-2023-51766

JSON object : View

Products Affected

fedoraproject

  • extra_packages_for_enterprise_linux
  • fedora

debian

  • debian_linux

exim

  • exim
CWE
CWE-345

Insufficient Verification of Data Authenticity