🛡️ CVE-2023-51766
🟡 CVSS 5.3 — Medium ⚠️ Exploit Public CWE-345 NVD
5.3
CVSS Score
0 Low4 Medium7 High9 Critical10

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 . but some other popular e-mail servers do not.

Details

Severity MEDIUM
CVSS Score 5.3
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
CWE CWE-345
Public Exploit ⚠️ Yes
Source NVD
Published 2023-12-24
Updated 2026-06-08
Modified 2025-11-04

Affected Packages

Software From version Fixed in
debian-linux — —
exim — 4.97.1
extra-packages-for-enterprise-linux — —
fedora — —

References

Mailing List, Third Party Advisory http://www.openwall.com/lists/oss-security/2023/12/24/1
Mailing List, Third Party Advisory http://www.openwall.com/lists/oss-security/2023/12/25/1
Mailing List, Mitigation, Third Party Advisory http://www.openwall.com/lists/oss-security/2023/12/29/2
Mailing List, Third Party Advisory http://www.openwall.com/lists/oss-security/2024/01/01/1
Mailing List, Third Party Advisory http://www.openwall.com/lists/oss-security/2024/01/01/2
Mailing List, Third Party Advisory http://www.openwall.com/lists/oss-security/2024/01/01/3
Issue Tracking, Vendor Advisory https://bugs.exim.org/show_bug.cgi?id=3063
Issue Tracking, Third Party Advisory https://bugzilla.redhat.com/show_bug.cgi?id=2255852
Third Party Advisory https://lwn.net/Articles/956533/
Issue Tracking, Mailing List, Third Party Advisory https://www.openwall.com/lists/oss-security/2023/12/23/2
Mailing List, Third Party Advisory http://www.openwall.com/lists/oss-security/2023/12/24/1
Mailing List, Third Party Advisory http://www.openwall.com/lists/oss-security/2023/12/25/1
Mailing List, Mitigation, Third Party Advisory http://www.openwall.com/lists/oss-security/2023/12/29/2
Mailing List, Third Party Advisory http://www.openwall.com/lists/oss-security/2024/01/01/1
Mailing List, Third Party Advisory http://www.openwall.com/lists/oss-security/2024/01/01/2
Mailing List, Third Party Advisory http://www.openwall.com/lists/oss-security/2024/01/01/3
Issue Tracking, Vendor Advisory https://bugs.exim.org/show_bug.cgi?id=3063
Issue Tracking, Third Party Advisory https://bugzilla.redhat.com/show_bug.cgi?id=2255852
Third Party Advisory https://lwn.net/Articles/956533/
Issue Tracking, Mailing List, Third Party Advisory https://www.openwall.com/lists/oss-security/2023/12/23/2

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