U.S. flag   An official website of the United States government
Dot gov

Official websites use .gov
A .gov website belongs to an official government organization in the United States.


Secure .gov websites use HTTPS
A lock (Dot gov) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

NOTICE UPDATED - May, 29th 2024

The NVD has a new announcement page with status updates, news, and how to stay connected!

CVE-2023-51766 Detail


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.


CVSS 4.0 Severity and Metrics:

NVD assessment not yet provided.

NVD Analysts use publicly available information to associate vector strings and CVSS scores. We also display any CVSS information provided within the CVE List from the CNA.

Note: NVD Analysts have not published a CVSS score for this CVE at this time. NVD Analysts use publicly available information at the time of analysis to associate CVSS vector strings.

References to Advisories, Solutions, and Tools

By selecting these links, you will be leaving NIST webspace. We have provided these links to other web sites because they may have information that would be of interest to you. No inferences should be drawn on account of other sites being referenced, or not, from this page. There may be other web sites that are more appropriate for your purpose. NIST does not necessarily endorse the views expressed, or concur with the facts presented on these sites. Further, NIST does not endorse any commercial products that may be mentioned on these sites. Please address comments about this page to nvd@nist.gov.

Hyperlink 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 

Weakness Enumeration

CWE-ID CWE Name Source
CWE-345 Insufficient Verification of Data Authenticity cwe source acceptance level NIST  

Known Affected Software Configurations Switch to CPE 2.2

CPEs loading, please wait.

Denotes Vulnerable Software
Are we missing a CPE here? Please let us know.

Change History

16 change records found show changes

Quick Info

CVE Dictionary Entry:
NVD Published Date:
NVD Last Modified: