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.

The remote Ubuntu 14.04 LTS / 16.04 LTS / 18.04 LTS / 20.04 LTS host has packages installed that are affected by multiple vulnerabilities as referenced in the USN-8382-1 advisory.

    Timo Longin discovered that Exim incorrectly handled certain SMTP messages in PIPELINING/CHUNKING     configurations. A remote attacker could possibly use this issue to perform SMTP smuggling. This issue only     affected Ubuntu 14.04 LTS. (CVE-2023-51766)

    It was discovered that Exim incorrectly handled certain malformed JSON data in headers. A remote attacker     could possibly use this issue to crash Exim, resulting in a denial of service, or execute arbitrary code.
    This issue only affected Ubuntu 20.04 LTS. (CVE-2026-40685)

    It was discovered that Exim incorrectly handled certain malformed UTF-8 headers. A remote attacker could     possibly use this issue to obtain sensitive information. This issue only affected Ubuntu 20.04 LTS.
    (CVE-2026-40686)

    It was discovered that Exim incorrectly handled certain SPA resources. A remote attacker could possibly     use this issue to crash Exim, resulting in a denial of service, or obtain sensitive information. This     issue only affected Ubuntu 20.04 LTS. (CVE-2026-40687)

    It was discovered that Exim incorrectly handled certain CHUNKING transfers in some GnuTLS configurations.
    A remote attacker could possibly use this issue to crash Exim, resulting in a denial of service, or     execute arbitrary code. This issue only affected Ubuntu 20.04 LTS. (CVE-2026-45185)

    Warisjeet Singh discovered that Exim incorrectly handled certain proxy connections in builds with proxy     support enabled. A remote attacker could possibly use this issue to obtain sensitive information. This     issue only affected Ubuntu 16.04 LTS, Ubuntu 18.04 LTS, and Ubuntu 20.04 LTS. (CVE-2026-48840)

Tenable has extracted the preceding description block directly from the Ubuntu security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote Debian 10 host has packages installed that are affected by a vulnerability as referenced in the dla-3708 advisory.

    -------------------------------------------------------------------------     Debian LTS Advisory DLA-3708-1                debian-lts@lists.debian.org     https://www.debian.org/lts/security/                      Markus Koschany     January 05, 2024                              https://wiki.debian.org/LTS
    -------------------------------------------------------------------------

    Package        : exim4     Version        : 4.92-8+deb10u9     CVE ID         : CVE-2023-51766     Debian Bug     : 1059387

    It was discovered that Exim, a mail transport agent, can be induced to accept a     second message embedded as part of the body of a first message in certain     configurations where PIPELINING or CHUNKING on incoming connections is offered.

    For Debian 10 buster, this problem has been fixed in version     4.92-8+deb10u9.

    We recommend that you upgrade your exim4 packages.

    For the detailed security status of exim4 please refer to     its security tracker page at:
    https://security-tracker.debian.org/tracker/exim4

    Further information about Debian LTS security advisories, how to apply     these updates to your system and frequently asked questions can be     found at: https://wiki.debian.org/LTS     Attachment:
    signature.asc     Description: This is a digitally signed message part

Tenable has extracted the preceding description block directly from the Debian security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The remote host is affected by the vulnerability described in GLSA-202402-18 (Exim: Multiple Vulnerabilities)

  - 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. (CVE-2023-51766)

  - NTLM Challenge Out-Of-Bounds Read Information Disclosure Vulnerability [epel-all] (CVE-2023-42114)

  - AUTH Out-Of-Bounds Write Remote Code Execution Vulnerability [epel-all] (CVE-2023-42115)

  - Exim SMTP Challenge Stack-based Buffer Overflow Remote Code Execution Vulnerability (CVE-2023-42116,     CVE-2023-42117)

  - dnsdb Out-Of-Bounds Read Information Disclosure Vulnerability [epel-all] (CVE-2023-42119)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote Ubuntu 16.04 ESM / 18.04 ESM / 20.04 LTS / 22.04 LTS / 23.10 host has packages installed that are affected by a vulnerability as referenced in the USN-6611-1 advisory.

    It was discovered that Exim incorrectly handled certain requests. A remote attacker could possibly use a     published exploitation technique to inject e-mail messages with a spoofed MAIL FROM address, allowing     bypass of an SPF protection mechanism.

Tenable has extracted the preceding description block directly from the Ubuntu security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The version of exim installed on the remote host is prior to 4.92-1.40. It is, therefore, affected by a vulnerability as referenced in the ALAS-2024-1908 advisory.

    Exim through 4.97 allows SMTP smuggling in certain 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. (CVE-2023-51766)

Tenable has extracted the preceding description block directly from the tested product security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The remote Fedora 38 host has a package installed that is affected by multiple vulnerabilities as referenced in the FEDORA-2024-e0841c83bb advisory.

    Security fix for CVE-2023-51766.

Tenable has extracted the preceding description block directly from the Fedora security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote Fedora 39 host has a package installed that is affected by multiple vulnerabilities as referenced in the FEDORA-2024-1ef6197a49 advisory.

    =Security fix for CVE-2023-51766.

Tenable has extracted the preceding description block directly from the Fedora security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote openSUSE 15 host has packages installed that are affected by multiple vulnerabilities as referenced in the openSUSE-SU-2024:0007-1 advisory.

  - A vulnerability was found in Exim and classified as problematic. This issue affects some unknown     processing of the component Regex Handler. The manipulation leads to use after free. The name of the patch     is 4e9ed49f8f12eb331b29bd5b6dc3693c520fddc2. It is recommended to apply a patch to fix this issue. The     identifier VDB-211073 was assigned to this vulnerability. (CVE-2022-3559)

  - NTLM Challenge Out-Of-Bounds Read Information Disclosure Vulnerability [epel-all] (CVE-2023-42114)

  - AUTH Out-Of-Bounds Write Remote Code Execution Vulnerability [epel-all] (CVE-2023-42115)

  - Exim SMTP Challenge Stack-based Buffer Overflow Remote Code Execution Vulnerability (CVE-2023-42116,     CVE-2023-42117)

  - dnsdb Out-Of-Bounds Read Information Disclosure Vulnerability [epel-all] (CVE-2023-42119)

  - 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. (CVE-2023-51766)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

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.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

There are packages installed that are affected by a vulnerability referenced in the following CVE:

  - 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. (CVE-2023-51766)

ID	Name	Product	Family	Severity
318625	Ubuntu 14.04 LTS / 16.04 LTS / 18.04 LTS / 20.04 LTS : Exim vulnerabilities (USN-8382-1)	Nessus	Ubuntu Local Security Checks	critical
214479	Debian dla-3708 : exim4 - security update	Nessus	Debian Local Security Checks	medium
190665	GLSA-202402-18 : Exim: Multiple Vulnerabilities	Nessus	Gentoo Local Security Checks	critical
189736	Ubuntu 16.04 ESM / 18.04 ESM / 20.04 LTS / 22.04 LTS / 23.10 : Exim vulnerability (USN-6611-1)	Nessus	Ubuntu Local Security Checks	medium
189390	Amazon Linux AMI : exim (ALAS-2024-1908)	Nessus	Amazon Linux Local Security Checks	medium
187964	Fedora 38 : exim (2024-e0841c83bb)	Nessus	Fedora Local Security Checks	medium
187963	Fedora 39 : exim (2024-1ef6197a49)	Nessus	Fedora Local Security Checks	medium
187650	openSUSE 15 Security Update : exim (openSUSE-SU-2024:0007-1)	Nessus	SuSE Local Security Checks	critical
187639	Exim < 4.97.1 SMTP smuggling	Nessus	SMTP problems	medium
408214	Alpine: multiple exim packages: security update to 4.97.1-r0	Tenable Cloud Security	Alpine Linux Local Security Checks	medium
408214	Alpine: multiple exim packages: security update to 4.97.1-r0	Tenable Self-Hosted Container Security	Alpine Linux Local Security Checks	medium

Detections

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CVE-2023-51766

medium

Tenable Plugins

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critical

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medium

medium

medium

critical

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medium