CVE-2023-51764
What it is
Postfix through 3.8.5 allows SMTP smuggling unless configured with smtpd_data_restrictions=reject_unauth_pipelining and smtpd_discard_ehlo_keywords=chunking (or certain other options that exist in recent versions). 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 Postfix supports <LF>.<CR><LF> but some other popular e-mail servers do not. To prevent attack variants (by always disallowing <LF> without <CR>), a different solution is required, such as the smtpd_forbid_bare_newline=yes option with a Postfix minimum version of 3.5.23, 3.6.13, 3.7.9, 3.8.4, or 3.9.
At a glance
- Exploitability
- Can be exploited over the network without logging in. Limited direct impact.
- Exploit odds
- 2.6% chance of exploitation in the next 30 days (EPSS).
- Fix
- A patch, advisory or fixed version is referenced. Upgrade or apply it.
Timeline
- PublishedDisclosed publicly on CVE.org and NVD
- Last updatedMost recent change to the record
Why it ranks here
- Exploited in the wild: no, CISA does not list it.
- Exploit odds: 2.6% in the next 30 days (EPSS).
- Severity: 5.3 MEDIUM (CVSS).
- Fix: a patch or advisory is linked.
Details
- Published
- Last modified
- Exploit probability
- 2.6% · EPSS, next 30 days
- Weakness
- CWE-345
- Record status
- Modified
Affected
- Postfix < 3.5.23
- Postfix < 3.6.13
- Postfix < 3.7.9
- Postfix < 3.8.4
- Fedoraproject Fedora 38
- Fedoraproject Fedora 39
- Redhat Enterprise Linux 8.0
- Redhat Enterprise Linux 9.0
Attack profile CVSS 3.1 · 5.3
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- Low
- Availability
- None
Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Is it in your code?
Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.
Read https://cve-list.com/agent/cve/CVE-2023-51764.md and follow it. Check whether this project is affected by CVE-2023-51764. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.
Fix and advisories
References
- http://www.openwall.com/lists/oss-security/2023/12/24/1
- http://www.openwall.com/lists/oss-security/2023/12/25/1
- http://www.openwall.com/lists/oss-security/2024/05/09/3
- https://access.redhat.com/security/cve/CVE-2023-51764
- https://bugzilla.redhat.com/show_bug.cgi?id=2255563
- https://fahrplan.events.ccc.de/congress/2023/fahrplan/events/11782.html
- https://github.com/duy-31/CVE-2023-51764
- https://github.com/eeenvik1/CVE-2023-51764
- https://lists.debian.org/debian-lts-announce/2024/01/msg00020.html
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/JQ5WXFCW2N6G2PH3JXDTYW5PH5EBQEGO/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QRLF5SOS7TP5N7FQSEK2NFNB44ISVTZC/
- https://lwn.net/Articles/956533/
- https://sec-consult.com/blog/detail/smtp-smuggling-spoofing-e-mails-worldwide/
- https://www.openwall.com/lists/oss-security/2024/01/22/1
- https://www.postfix.org/announcements/postfix-3.8.5.html
- https://www.postfix.org/smtp-smuggling.html
- https://www.youtube.com/watch?v=V8KPV96g1To
- http://www.openwall.com/lists/oss-security/2023/12/24/1
- http://www.openwall.com/lists/oss-security/2023/12/25/1
- http://www.openwall.com/lists/oss-security/2024/05/09/3
- https://access.redhat.com/security/cve/CVE-2023-51764
- https://bugzilla.redhat.com/show_bug.cgi?id=2255563
- https://fahrplan.events.ccc.de/congress/2023/fahrplan/events/11782.html
- https://github.com/duy-31/CVE-2023-51764
- https://github.com/eeenvik1/CVE-2023-51764