CVE-2023-51766

Publication date 24 December 2023

Last updated 19 August 2025

Ubuntu priority

Medium

Why this priority?

Cvss 3 Severity Score

5.3 · Medium

Score breakdown

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.

Status

Package Ubuntu Release Status
exim4 25.10 questing
Fixed 4.97-3
25.04 plucky
Fixed 4.97-3
24.10 oracular
Fixed 4.97-3
24.04 LTS noble
Fixed 4.97-3
23.10 mantic
Fixed 4.96-17ubuntu2.2
23.04 lunar Ignored end of life, was needs-triage
22.04 LTS jammy
Fixed 4.95-4ubuntu2.5
20.04 LTS focal
Fixed 4.93-13ubuntu1.10
18.04 LTS bionic
Fixed 4.90.1-1ubuntu1.10+esm3
16.04 LTS xenial
Fixed 4.86.2-2ubuntu2.6+esm6
14.04 LTS trusty
Needs evaluation

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Severity score breakdown

Parameter Value
Base score 5.3 · Medium
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Scope Unchanged
Confidentiality None
Integrity impact Low
Availability impact None
Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

References

Related Ubuntu Security Notices (USN)

Other references