CVE-2023-51765sendmail through 8.17.2 allows SMTP smuggling in certain configurations. Remote attackers can use a published exploitation technique to…
- 5.3MediumCVSS base score
- 1.1%Exploitation in 30 daysEPSS · top 34% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
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.
Timeline
Published
- 7 months later
· 7 months later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| NVDNVD · Modified | 3.1 | Medium5.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N |
- EPSS (exploitation in 30 days)
- 1.1% · top 34% of all CVEs (13 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 5.3.
Affected products
n/a
- affected n/a
References
References17
- https://sec-consult.com/blog/detail/smtp-smuggling-spoofing-e-mails-worldwide/ (opens in a new tab)x_transferred
- https://www.openwall.com/lists/oss-security/2023/12/22/7 (opens in a new tab)x_transferred
- https://www.openwall.com/lists/oss-security/2023/12/21/7 (opens in a new tab)x_transferred
- https://github.com/freebsd/freebsd-src/commit/5dd76dd0cc19450133aa379ce0ce4a68ae07fb39#diff-afdf514b32ac88004952c11660c57bc96c3d8b2234007c1cbd8d7ed7fd7935cc (opens in a new tab)x_transferred
- [oss-security] 20231224 Re: Re: New SMTP smuggling attack (opens in a new tab)mailing-listx_transferred
- [oss-security] 20231225 Re: Re: New SMTP smuggling attack (opens in a new tab)mailing-listx_transferred
- https://bugzilla.suse.com/show_bug.cgi?id=1218351 (opens in a new tab)x_transferred
- https://bugzilla.redhat.com/show_bug.cgi?id=2255869 (opens in a new tab)x_transferred
- https://access.redhat.com/security/cve/CVE-2023-51765 (opens in a new tab)x_transferred
- https://fahrplan.events.ccc.de/congress/2023/fahrplan/events/11782.html (opens in a new tab)x_transferred
- [oss-security] 20231226 Re: New SMTP smuggling attack (opens in a new tab)mailing-listx_transferred
- [oss-security] 20231229 Re: Re: New SMTP smuggling attack (opens in a new tab)mailing-listx_transferred
- [oss-security] 20231230 Re: Re: New SMTP smuggling attack (opens in a new tab)mailing-listx_transferred
- [oss-security] 20231230 Re: Re: New SMTP smuggling attack (opens in a new tab)mailing-listx_transferred
- https://www.youtube.com/watch?v=V8KPV96g1To (opens in a new tab)x_transferred
- https://lwn.net/Articles/956533/ (opens in a new tab)x_transferred
- [debian-lts-announce] 20240615 [SECURITY] [DLA 3829-1] sendmail security update (opens in a new tab)mailing-listx_transferred
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2023-56454 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2023-51765)Record last updated .