vulnerability
Exim: Insufficient Verification of Data Authenticity (CVE-2023-51766)
| Severity | CVSS | Published | Added | Modified |
|---|---|---|---|---|
| 5 | (AV:N/AC:L/Au:N/C:N/I:P/A:N) | Dec 24, 2023 | Jan 8, 2024 | Apr 7, 2026 |
Severity
5
CVSS
(AV:N/AC:L/Au:N/C:N/I:P/A:N)
Published
Dec 24, 2023
Added
Jan 8, 2024
Modified
Apr 7, 2026
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.
Solution
exim-upgrade-4_97_1
References
Rapid7 Labs
2026 Global Threat Landscape Report
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