An attacker can send crafted DNS over HTTP/3 queries, triggering an exception that prevents some buffer from being freed right away. The buffer will be freed at the end of the QUIC connection, but on some setups it might be possible to open enough concurrent DoH3 streams to trigger an out-of-memory condition, resulting in a denial of service.

The version of FreeBSD installed on the remote host is prior to tested version. It is, therefore, affected by multiple vulnerabilities as referenced in the 6c0e17cf-73a0-11f1-910d-3c7c3fba4204 advisory.

    The DNSdist team reports:
    Thanks to people below for reporting these vulnerabilities.

Tenable has extracted the preceding description block directly from the FreeBSD 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.

  - An attacker can send crafted DNS over HTTP/3 queries, triggering an exception that prevents some buffer     from being freed right away. The buffer will be freed at the end of the QUIC connection, but on some     setups it might be possible to open enough concurrent DoH3 streams to trigger an out-of-memory condition,     resulting in a denial of service. (CVE-2026-40211)

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

The remote Debian 13 host has a package installed that is affected by multiple vulnerabilities as referenced in the dsa-6367 advisory.

    - -------------------------------------------------------------------------     Debian Security Advisory DSA-6367-1                   security@debian.org     https://www.debian.org/security/                       Moritz Muehlenhoff     June 25, 2026                         https://www.debian.org/security/faq
    - -------------------------------------------------------------------------

    Package        : dnsdist     CVE ID         : CVE-2026-40011 CVE-2026-40208 CVE-2026-40209                      CVE-2026-40210 CVE-2026-40211 CVE-2026-42004                      CVE-2026-42005

    Multiple security vulnerabilities were discovered in the dnsdist DNS     loadbalancer, which could result in denial of service, information     disclosure or bypass of security rules.

    For the stable distribution (trixie), these problems have been fixed in     version 1.9.15-0+deb13u1.

    We recommend that you upgrade your dnsdist packages.

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

    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.

ID	Name	Product	Family	Severity
323686	FreeBSD : DNSdist -- vulnerabilities (6c0e17cf-73a0-11f1-910d-3c7c3fba4204)	Nessus	FreeBSD Local Security Checks	medium
323424	Linux Distros Unpatched Vulnerability : CVE-2026-40211	Nessus	Misc.	medium
322938	Debian dsa-6367 : dnsdist - security update	Nessus	Debian Local Security Checks	medium

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CVE-2026-40211

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Tenable Plugins

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