CVE-2023-51766

Medium

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.

SeverityMedium

CVSS5.3

Exploit probability—

Product

Exim

PublishedDec 24, 2023

First seenDec 24, 2023

How to fix

Update

exim exim4.97.1 or later

Vendor advisories

lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QPDWHJPABVJCXDSNELSSVTIVAJU2MDUQ/
lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ORN7OKEQPPBKUHYRQ6LR5PSNBQVDHAWB/

Affected products

Product	Affected versions	Fixed in
exim exim	v < 4.97.1	4.97.1
fedoraproject extra_packages_for_enterprise_linux	7.0, 8.0, 9.0	—
fedoraproject fedora	38, 39	—
debian debian_linux	10.0	—

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