CVE-2023-51766

MEDIUM
5.3
CVSS Score
Published: December 24, 2023 at 12:00 AM UTC
Updated: June 17, 2026 at 06:41 AM UTC
4 products affected across 3 vendorsDebian LinuxFedoraExtra Packages for Enterprise Linux

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Severity
MEDIUM5.3
Exploit prediction
EPSS 1%

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 4.97.1
Affected range stops below 4.97.1, so it looks safe — our inference, not a vendor statement

CVSS

Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
LOW
Availability
NONE
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-345

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