5.3
MEDIUM
CVE-2023-51766
Exim SMTP Smuggling Vulnerability
Description

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.

INFO

Published Date :

Dec. 24, 2023, 6:15 a.m.

Last Modified :

Feb. 2, 2024, 2:22 a.m.

Source :

[email protected]

Remotely Exploitable :

Yes !

Impact Score :

1.4

Exploitability Score :

3.9
Public PoC/Exploit Available at Github

CVE-2023-51766 has a 2 public PoC/Exploit available at Github. Go to the Public Exploits tab to see the list.

Affected Products

The following products are affected by CVE-2023-51766 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

ID Vendor Product Action
1 Fedoraproject fedora
2 Fedoraproject extra_packages_for_enterprise_linux
1 Debian debian_linux
1 Exim exim
: Total Affected Vendor : 3 | Products : 4
References to Advisories, Solutions, and Tools

Here, you will find a curated list of external links that provide in-depth information, practical solutions, and valuable tools related to CVE-2023-51766.

URL 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

We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).

Profile Photo
Farrhouq/Inpt-report

Imoro Umar Farouq's report on Internal Network Penetration Testing

Shell

Updated: 2 weeks, 6 days ago
0 stars 0 fork 0 watcher
Born at : Sept. 12, 2024, 11:46 a.m. This repo has been linked 161 different CVEs too.
Profile Photo
hannob/smtpsmug

None

Python Shell

Updated: 2 months, 2 weeks ago
94 stars 13 fork 13 watcher
Born at : Dec. 21, 2023, 8:13 p.m. This repo has been linked 3 different CVEs too.

Results are limited to the first 15 repositories due to potential performance issues.

The following list is the news that have been mention CVE-2023-51766 vulnerability anywhere in the article.

The following table lists the changes that have been made to the CVE-2023-51766 vulnerability over time.

Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.

  • CVE Modified by [email protected]

    May. 14, 2024

    Action Type Old Value New Value
  • Modified Analysis by [email protected]

    Feb. 02, 2024

    Action Type Old Value New Value
    Removed CVSS V3.1 NIST AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N
    Added CVSS V3.1 NIST AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
    Changed Reference Type https://lists.debian.org/debian-lts-announce/2024/01/msg00002.html No Types Assigned https://lists.debian.org/debian-lts-announce/2024/01/msg00002.html Mailing List, Third Party Advisory
    Changed Reference Type https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ORN7OKEQPPBKUHYRQ6LR5PSNBQVDHAWB/ No Types Assigned https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ORN7OKEQPPBKUHYRQ6LR5PSNBQVDHAWB/ Mailing List, Third Party Advisory
    Changed Reference Type https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QPDWHJPABVJCXDSNELSSVTIVAJU2MDUQ/ No Types Assigned https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QPDWHJPABVJCXDSNELSSVTIVAJU2MDUQ/ Mailing List, Third Party Advisory
    Changed Reference Type https://lwn.net/Articles/956533/ No Types Assigned https://lwn.net/Articles/956533/ Third Party Advisory
    Changed Reference Type https://www.youtube.com/watch?v=V8KPV96g1To No Types Assigned https://www.youtube.com/watch?v=V8KPV96g1To Exploit
    Added CPE Configuration OR *cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
  • CVE Modified by [email protected]

    Jan. 18, 2024

    Action Type Old Value New Value
    Added Reference MITRE https://lwn.net/Articles/956533/ [No types assigned]
  • CVE Modified by [email protected]

    Jan. 12, 2024

    Action Type Old Value New Value
    Added Reference MITRE https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QPDWHJPABVJCXDSNELSSVTIVAJU2MDUQ/ [No types assigned]
    Added Reference MITRE https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ORN7OKEQPPBKUHYRQ6LR5PSNBQVDHAWB/ [No types assigned]
  • CVE Modified by [email protected]

    Jan. 05, 2024

    Action Type Old Value New Value
    Added Reference MITRE https://lists.debian.org/debian-lts-announce/2024/01/msg00002.html [No types assigned]
  • CVE Modified by [email protected]

    Jan. 04, 2024

    Action Type Old Value New Value
    Added Reference MITRE https://www.youtube.com/watch?v=V8KPV96g1To [No types assigned]
  • Initial Analysis by [email protected]

    Jan. 04, 2024

    Action Type Old Value New Value
    Added CVSS V3.1 NIST AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N
    Changed Reference Type http://www.openwall.com/lists/oss-security/2023/12/24/1 No Types Assigned http://www.openwall.com/lists/oss-security/2023/12/24/1 Mailing List, Third Party Advisory
    Changed Reference Type http://www.openwall.com/lists/oss-security/2023/12/25/1 No Types Assigned http://www.openwall.com/lists/oss-security/2023/12/25/1 Mailing List, Third Party Advisory
    Changed Reference Type http://www.openwall.com/lists/oss-security/2023/12/29/2 No Types Assigned http://www.openwall.com/lists/oss-security/2023/12/29/2 Mailing List, Mitigation, Third Party Advisory
    Changed Reference Type http://www.openwall.com/lists/oss-security/2024/01/01/1 No Types Assigned http://www.openwall.com/lists/oss-security/2024/01/01/1 Mailing List, Third Party Advisory
    Changed Reference Type http://www.openwall.com/lists/oss-security/2024/01/01/2 No Types Assigned http://www.openwall.com/lists/oss-security/2024/01/01/2 Mailing List, Third Party Advisory
    Changed Reference Type http://www.openwall.com/lists/oss-security/2024/01/01/3 No Types Assigned http://www.openwall.com/lists/oss-security/2024/01/01/3 Mailing List, Third Party Advisory
    Changed Reference Type https://bugs.exim.org/show_bug.cgi?id=3063 No Types Assigned https://bugs.exim.org/show_bug.cgi?id=3063 Issue Tracking, Vendor Advisory
    Changed Reference Type https://bugzilla.redhat.com/show_bug.cgi?id=2255852 No Types Assigned https://bugzilla.redhat.com/show_bug.cgi?id=2255852 Issue Tracking, Third Party Advisory
    Changed Reference Type https://exim.org/static/doc/security/CVE-2023-51766.txt No Types Assigned https://exim.org/static/doc/security/CVE-2023-51766.txt Broken Link
    Changed Reference Type https://fahrplan.events.ccc.de/congress/2023/fahrplan/events/11782.html No Types Assigned https://fahrplan.events.ccc.de/congress/2023/fahrplan/events/11782.html Technical Description
    Changed Reference Type https://git.exim.org/exim.git/commit/5bb786d5ad568a88d50d15452aacc8404047e5ca No Types Assigned https://git.exim.org/exim.git/commit/5bb786d5ad568a88d50d15452aacc8404047e5ca Patch
    Changed Reference Type https://git.exim.org/exim.git/commit/cf1376206284f2a4f11e32d931d4aade34c206c5 No Types Assigned https://git.exim.org/exim.git/commit/cf1376206284f2a4f11e32d931d4aade34c206c5 Patch
    Changed Reference Type https://github.com/Exim/exim/blob/master/doc/doc-txt/cve-2023-51766 No Types Assigned https://github.com/Exim/exim/blob/master/doc/doc-txt/cve-2023-51766 Mitigation, Vendor Advisory
    Changed Reference Type https://sec-consult.com/blog/detail/smtp-smuggling-spoofing-e-mails-worldwide/ No Types Assigned https://sec-consult.com/blog/detail/smtp-smuggling-spoofing-e-mails-worldwide/ Technical Description, Third Party Advisory
    Changed Reference Type https://www.openwall.com/lists/oss-security/2023/12/23/2 No Types Assigned https://www.openwall.com/lists/oss-security/2023/12/23/2 Issue Tracking, Mailing List, Third Party Advisory
    Added CWE NIST CWE-345
    Added CPE Configuration OR *cpe:2.3:a:exim:exim:*:*:*:*:*:*:*:* versions up to (excluding) 4.97.1
    Added CPE Configuration 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:*:*:*:*:*:*:*
  • CVE Modified by [email protected]

    Jan. 02, 2024

    Action Type Old Value New Value
    Added Reference MITRE http://www.openwall.com/lists/oss-security/2024/01/01/3 [No types assigned]
  • CVE Modified by [email protected]

    Jan. 01, 2024

    Action Type Old Value New Value
    Added Reference MITRE http://www.openwall.com/lists/oss-security/2024/01/01/2 [No types assigned]
  • CVE Modified by [email protected]

    Jan. 01, 2024

    Action Type Old Value New Value
    Added Reference MITRE http://www.openwall.com/lists/oss-security/2024/01/01/1 [No types assigned]
  • CVE Modified by [email protected]

    Jan. 01, 2024

    Action Type Old Value New Value
    Changed Description Exim through 4.97 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 Exim supports <LF>.<CR><LF> but some other popular e-mail servers do not. 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.
    Added Reference MITRE https://github.com/Exim/exim/blob/master/doc/doc-txt/cve-2023-51766 [No types assigned]
  • CVE Modified by [email protected]

    Dec. 29, 2023

    Action Type Old Value New Value
    Added Reference MITRE http://www.openwall.com/lists/oss-security/2023/12/29/2 [No types assigned]
  • CVE Modified by [email protected]

    Dec. 26, 2023

    Action Type Old Value New Value
    Added Reference MITRE https://fahrplan.events.ccc.de/congress/2023/fahrplan/events/11782.html [No types assigned]
  • CVE Modified by [email protected]

    Dec. 26, 2023

    Action Type Old Value New Value
    Changed Description Exim through 4.97 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 Exim server, allowing bypass of an SPF protection mechanism. This occurs because Exim supports <LF>.<CR><LF> but some other popular e-mail servers do not. Exim through 4.97 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 Exim supports <LF>.<CR><LF> but some other popular e-mail servers do not.
    Added Reference MITRE http://www.openwall.com/lists/oss-security/2023/12/25/1 [No types assigned]
    Added Reference MITRE https://git.exim.org/exim.git/commit/5bb786d5ad568a88d50d15452aacc8404047e5ca [No types assigned]
    Added Reference MITRE https://git.exim.org/exim.git/commit/cf1376206284f2a4f11e32d931d4aade34c206c5 [No types assigned]
    Added Reference MITRE https://bugzilla.redhat.com/show_bug.cgi?id=2255852 [No types assigned]
  • CVE Modified by [email protected]

    Dec. 24, 2023

    Action Type Old Value New Value
    Added Reference MITRE http://www.openwall.com/lists/oss-security/2023/12/24/1 [No types assigned]
  • CVE Received by [email protected]

    Dec. 24, 2023

    Action Type Old Value New Value
    Added Description Exim through 4.97 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 Exim server, allowing bypass of an SPF protection mechanism. This occurs because Exim supports <LF>.<CR><LF> but some other popular e-mail servers do not.
    Added Reference MITRE https://sec-consult.com/blog/detail/smtp-smuggling-spoofing-e-mails-worldwide/ [No types assigned]
    Added Reference MITRE https://exim.org/static/doc/security/CVE-2023-51766.txt [No types assigned]
    Added Reference MITRE https://bugs.exim.org/show_bug.cgi?id=3063 [No types assigned]
    Added Reference MITRE https://www.openwall.com/lists/oss-security/2023/12/23/2 [No types assigned]
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days. Following chart shows the EPSS score history of the vulnerability.
CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2023-51766 is associated with the following CWEs:

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2023-51766 weaknesses.

CAPEC-111: JSON Hijacking (aka JavaScript Hijacking) JSON Hijacking (aka JavaScript Hijacking) CAPEC-141: Cache Poisoning Cache Poisoning CAPEC-142: DNS Cache Poisoning DNS Cache Poisoning CAPEC-148: Content Spoofing Content Spoofing CAPEC-218: Spoofing of UDDI/ebXML Messages Spoofing of UDDI/ebXML Messages CAPEC-384: Application API Message Manipulation via Man-in-the-Middle Application API Message Manipulation via Man-in-the-Middle CAPEC-385: Transaction or Event Tampering via Application API Manipulation Transaction or Event Tampering via Application API Manipulation CAPEC-386: Application API Navigation Remapping Application API Navigation Remapping CAPEC-387: Navigation Remapping To Propagate Malicious Content Navigation Remapping To Propagate Malicious Content CAPEC-388: Application API Button Hijacking Application API Button Hijacking CAPEC-665: Exploitation of Thunderbolt Protection Flaws Exploitation of Thunderbolt Protection Flaws CAPEC-701: Browser in the Middle (BiTM) Browser in the Middle (BiTM)
Exploit Prediction

EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days.

0.28 }} 0.10%

score

0.64896

percentile

CVSS31 - Vulnerability Scoring System
Attack Vector
Attack Complexity
Privileges Required
User Interaction
Scope
Confidentiality
Integrity
Availability
: