In Exim before 4.99.2, when JSON lookup is enabled, an out-of-bounds heap write can occur when a JSON operator encounters malformed JSON in an untrusted header, because of an incorrect implementation of \ skipping.

The CentOS Linux 7 host has packages installed that are affected by multiple vulnerabilities as referenced in the TuxCare CENTOS7:CLSA-2026:1778173472 advisory.

  - In Exim before 4.99.2, when JSON lookup is enabled, an out-of-bounds heap write can occur when a JSON     operator encounters malformed JSON in an untrusted header, because of an incorrect implementation of \     skipping. (CVE-2026-40685)

  - In Exim before 4.99.2, when the SPA authentication driver is used with an adversarial SPA resource, there     can be an out-of-bounds write that crashes the connection instance, or erroneous data processing that     divulges data from uninitialized heap memory. (CVE-2026-40687)

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

The AlmaLinux 9.2 host has packages installed that are affected by multiple vulnerabilities as referenced in the TuxCare ALMALINUX9.2:CLSA-2026:1778297730 advisory.

  - In Exim before 4.99.2, when JSON lookup is enabled, an out-of-bounds heap write can occur when a JSON     operator encounters malformed JSON in an untrusted header, because of an incorrect implementation of \     skipping. (CVE-2026-40685)

  - In Exim before 4.99.2, when the SPA authentication driver is used with an adversarial SPA resource, there     can be an out-of-bounds write that crashes the connection instance, or erroneous data processing that     divulges data from uninitialized heap memory. (CVE-2026-40687)

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

The Rocky Linux 9.6 host has packages installed that are affected by multiple vulnerabilities as referenced in the TuxCare ALMALINUX9.6:CLSA-2026:1778690104 advisory.

  - In Exim before 4.99.2, when JSON lookup is enabled, an out-of-bounds heap write can occur when a JSON     operator encounters malformed JSON in an untrusted header, because of an incorrect implementation of \     skipping. (CVE-2026-40685)

  - In Exim before 4.99.2, when the SPA authentication driver is used with an adversarial SPA resource, there     can be an out-of-bounds write that crashes the connection instance, or erroneous data processing that     divulges data from uninitialized heap memory. (CVE-2026-40687)

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

The AlmaLinux 9.6 host has packages installed that are affected by multiple vulnerabilities as referenced in the TuxCare ALMALINUX9.6:CLSA-2026:1778690104 advisory.

  - In Exim before 4.99.2, when JSON lookup is enabled, an out-of-bounds heap write can occur when a JSON     operator encounters malformed JSON in an untrusted header, because of an incorrect implementation of \     skipping. (CVE-2026-40685)

  - In Exim before 4.99.2, when the SPA authentication driver is used with an adversarial SPA resource, there     can be an out-of-bounds write that crashes the connection instance, or erroneous data processing that     divulges data from uninitialized heap memory. (CVE-2026-40687)

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

The CentOS Linux 6 host has packages installed that are affected by a vulnerability as referenced in the TuxCare CENTOS6:CLSA-2026:1778147777 advisory.

  - In Exim before 4.99.2, when JSON lookup is enabled, an out-of-bounds heap write can occur when a JSON     operator encounters malformed JSON in an untrusted header, because of an incorrect implementation of \     skipping. (CVE-2026-40685)

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

The CentOS Linux 8.5 host has packages installed that are affected by multiple vulnerabilities as referenced in the TuxCare CENTOS8.5:CLSA-2026:1779531839 advisory.

  - In Exim before 4.99.2, when JSON lookup is enabled, an out-of-bounds heap write can occur when a JSON     operator encounters malformed JSON in an untrusted header, because of an incorrect implementation of \     skipping. (CVE-2026-40685)

  - In Exim before 4.99.2, when utf8 operators are enabled, there is an out-of-bounds read if large UTF-8     trailing characters are present (malformed UTF-8 header data). Information might be divulged within an     error message produced during handling of an unrelated e-mail message. (CVE-2026-40686)

  - In Exim before 4.99.2, when the SPA authentication driver is used with an adversarial SPA resource, there     can be an out-of-bounds write that crashes the connection instance, or erroneous data processing that     divulges data from uninitialized heap memory. (CVE-2026-40687)

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

The CentOS Linux 8.4 host has packages installed that are affected by multiple vulnerabilities as referenced in the TuxCare CENTOS8.4:CLSA-2026:1779531651 advisory.

  - In Exim before 4.99.2, when JSON lookup is enabled, an out-of-bounds heap write can occur when a JSON     operator encounters malformed JSON in an untrusted header, because of an incorrect implementation of \     skipping. (CVE-2026-40685)

  - In Exim before 4.99.2, when utf8 operators are enabled, there is an out-of-bounds read if large UTF-8     trailing characters are present (malformed UTF-8 header data). Information might be divulged within an     error message produced during handling of an unrelated e-mail message. (CVE-2026-40686)

  - In Exim before 4.99.2, when the SPA authentication driver is used with an adversarial SPA resource, there     can be an out-of-bounds write that crashes the connection instance, or erroneous data processing that     divulges data from uninitialized heap memory. (CVE-2026-40687)

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

The remote host is affected by the vulnerability described in GLSA-202608-07 (Exim: Multiple Vulnerabilities)

    Multiple vulnerabilities have been discovered in Exim. Please review the CVE identifiers referenced below     for details.

Tenable has extracted the preceding description block directly from the Gentoo Linux 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 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 12 / 13 host has packages installed that are affected by multiple vulnerabilities as referenced in the dsa-6265 advisory.

    - -------------------------------------------------------------------------     Debian Security Advisory DSA-6265-1                   security@debian.org     https://www.debian.org/security/                     Salvatore Bonaccorso     May 12, 2026                          https://www.debian.org/security/faq
    - -------------------------------------------------------------------------

    Package        : exim4     CVE ID         : CVE-2026-40684 CVE-2026-40685 CVE-2026-40686 CVE-2026-40687

    Several vulnerabilities were discovered in the Exim mail transport     agent, which may result in remote code execution, denial of service or     an information leak.

    For the oldstable distribution (bookworm), these problems have been fixed     in version 4.96-15+deb12u9.

    For the stable distribution (trixie), these problems have been fixed in     version 4.98.2-1+deb13u2.

    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 Security Advisories, how to apply     these updates to your system and frequently asked questions can be     found at: https://www.debian.org/security/

    Mailing list: debian-security-announce@lists.debian.org

Tenable has extracted the preceding description block directly from the Debian 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 Ubuntu 22.04 LTS / 24.04 LTS / 25.10 / 26.04 LTS host has packages installed that are affected by multiple vulnerabilities as referenced in the USN-8228-1 advisory.

    It was discovered that Exim incorrectly handled parsing malformed JSON in message headers. A remote     attacker could possibly use this issue to execute arbitrary code. (CVE-2026-40685)

    It was discovered that Exim incorrectly handled processing of UTF-8 trailing characters. A remote attacker     could possibly use this issue to obtain sensitive information. (CVE-2026-40686)

    It was discovered that Exim incorrectly handled SPA authenticator input. An authenticated user could     possibly use this issue to execute arbitrary code. (CVE-2026-40687)

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 Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - In Exim before 4.99.2, when JSON lookup is enabled, an out-of-bounds heap write can occur when a JSON     operator encounters malformed JSON in an untrusted header, because of an incorrect implementation of \     skipping. (CVE-2026-40685)

Note that Nessus relies on the presence of the package as reported by the vendor.

ID	Name	Product	Family	Type	Severity
362150	CentOS Linux 7 [TuxCare] Security Update: exim / exim-greylist / exim-mon / exim-mysql / exim-pgsql / etc Multiple Vulnerabilities (CENTOS7:CLSA-2026:1778173472)	Nessus	CentOS Local Security Checks	Local	critical
361501	AlmaLinux 9.2 [TuxCare] Security Update: exim / exim-greylist / exim-mon / exim-mysql / exim-pgsql Multiple Vulnerabilities (ALMALINUX9.2:CLSA-2026:1778297730)	Nessus	Alma Linux Local Security Checks	Local	critical
361484	Rocky Linux 9.6 [TuxCare] Security Update: exim / exim-greylist / exim-mon / exim-mysql / exim-pgsql Multiple Vulnerabilities (ALMALINUX9.6:CLSA-2026:1778690104)	Nessus	Rocky Linux Local Security Checks	Local	critical
361414	AlmaLinux 9.6 [TuxCare] Security Update: exim / exim-greylist / exim-mon / exim-mysql / exim-pgsql Multiple Vulnerabilities (ALMALINUX9.6:CLSA-2026:1778690104)	Nessus	Alma Linux Local Security Checks	Local	critical
353243	CentOS Linux 6 [TuxCare] Security Update: exim / exim-greylist / exim-mon / exim-mysql / exim-pgsql (CENTOS6:CLSA-2026:1778147777)	Nessus	CentOS Local Security Checks	Local	critical
351941	CentOS Linux 8.5 [TuxCare] Security Update: exim / exim-greylist / exim-mon / exim-mysql / exim-pgsql Multiple Vulnerabilities (CENTOS8.5:CLSA-2026:1779531839)	Nessus	CentOS Local Security Checks	Local	critical
351895	CentOS Linux 8.4 [TuxCare] Security Update: exim / exim-greylist / exim-mon / exim-mysql / exim-pgsql Multiple Vulnerabilities (CENTOS8.4:CLSA-2026:1779531651)	Nessus	CentOS Local Security Checks	Local	critical
335323	GLSA-202608-07 : Exim: Multiple Vulnerabilities	Nessus	Gentoo Local Security Checks	Local	critical
318625	Ubuntu 14.04 LTS / 16.04 LTS / 18.04 LTS / 20.04 LTS : Exim vulnerabilities (USN-8382-1)	Nessus	Ubuntu Local Security Checks	Local	critical
314336	Debian dsa-6265 : exim4 - security update	Nessus	Debian Local Security Checks	Local	critical
312296	Ubuntu 22.04 LTS / 24.04 LTS / 25.10 / 26.04 LTS : Exim vulnerabilities (USN-8228-1)	Nessus	Ubuntu Local Security Checks	Local	critical
311152	Linux Distros Unpatched Vulnerability : CVE-2026-40685	Nessus	Misc.	Local	critical

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