Exim before 4.99.3, in certain GnuTLS configurations, has a remotely reachable use-after-free in the BDAT body parsing path. It is triggered when a client sends a TLS close_notify mid-body during a CHUNKING transfer, followed by a final cleartext byte on the same TCP connection. This can lead to heap corruption. An unauthenticated network attacker exploiting this vulnerability could execute arbitrary code.

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

  - Exim before 4.99.3, in certain GnuTLS configurations, has a remotely reachable use-after-free in the BDAT     body parsing path. It is triggered when a client sends a TLS close_notify mid-body during a CHUNKING     transfer, followed by a final cleartext byte on the same TCP connection. This can lead to heap corruption.
    An unauthenticated network attacker exploiting this vulnerability could execute arbitrary code.
    (CVE-2026-45185)

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

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
315663	Linux Distros Unpatched Vulnerability : CVE-2026-45185	Nessus	Misc.	critical

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CVE-2026-45185

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