CVE-2023-51764

Exploitation

Not assessed. CISA has not published an exploitation assessment for this record, and it is not in the KEV catalog. That is an absence of assessment, not a finding of no risk.

SSVC decision

Not assessed by CISA

EPSS probability

2.63% probability of exploitation activity in the next 30 days.

EPSS percentile

Ranks above 84.5% of scored records. A rank, not a probability.

NVD base score

5.3 (CVSS v3.x), scored by the NVD independently of the CNA.

NVD CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

NVD analysis status

Modified. NVD last modified this record on 2026-06-17.

Red Hat severity

Moderate. Red Hat's rating for its own products, not a CVSS rating.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

Published

2023-12-24 00:00Z2 YR AGO

Last updated

2025-11-04 22:05Z10 MO AGO

Reserved

2023-12-24

Assigning CNA

mitre

Record state

PUBLISHED

Severity

Not rated by the issuing CNA

CNA CVSS vector

Not published by the issuing CNA

Weaknesses

• CWE-345Insufficient Verification of Data AuthenticityClass
• CWE-94Improper Control of Generation of Code ('Code Injection')Base

Data version

5.2

Document digest

4935c2506d5788d27650e287c9dbea5f8d5f6caa24f38eb4518c49b8b2a5b92c

• www.postfix.orghttps://www.postfix.org/smtp-smuggling.html
• sec-consult.comhttps://sec-consult.com/blog/detail/smtp-smuggling-spoofing-e-mails-worldwide/
• www.openwall.com[oss-security] 20231224 Re: Re: New SMTP smuggling attackhttp://www.openwall.com/lists/oss-security/2023/12/24/1mailing-list
• www.openwall.com[oss-security] 20231225 Re: Re: New SMTP smuggling attackhttp://www.openwall.com/lists/oss-security/2023/12/25/1mailing-list
• bugzilla.redhat.comhttps://bugzilla.redhat.com/show_bug.cgi?id=2255563
• access.redhat.comhttps://access.redhat.com/security/cve/CVE-2023-51764
• fahrplan.events.ccc.dehttps://fahrplan.events.ccc.de/congress/2023/fahrplan/events/11782.html
• github.comhttps://github.com/eeenvik1/CVE-2023-51764
• github.comhttps://github.com/duy-31/CVE-2023-51764
• www.youtube.comhttps://www.youtube.com/watch?v=V8KPV96g1To
• lists.fedoraproject.orgFEDORA-2024-c839e7294fhttps://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QRLF5SOS7TP5N7FQSEK2NFNB44ISVTZC/vendor-advisory
• lists.fedoraproject.orgFEDORA-2024-5c186175f2https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/JQ5WXFCW2N6G2PH3JXDTYW5PH5EBQEGO/vendor-advisory
• lwn.nethttps://lwn.net/Articles/956533/
• www.openwall.comhttps://www.openwall.com/lists/oss-security/2024/01/22/1
• www.postfix.orghttps://www.postfix.org/announcements/postfix-3.8.5.html
• lists.debian.org[debian-lts-announce] 20240130 [SECURITY] [DLA 3725-1] postfix security updatehttps://lists.debian.org/debian-lts-announce/2024/01/msg00020.htmlmailing-list
• www.openwall.com[oss-security] 20240508 Re: New SMTP smuggling attackhttp://www.openwall.com/lists/oss-security/2024/05/09/3mailing-list
• lists.fedoraproject.orghttps://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/QRLF5SOS7TP5N7FQSEK2NFNB44ISVTZC/
• lists.fedoraproject.orghttps://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/JQ5WXFCW2N6G2PH3JXDTYW5PH5EBQEGO/