A rogue backend can send a crafted SVCB response to a Discovery of Designated Resolvers request, when requested via either the autoUpgrade (Lua) option to newServer or auto_upgrade (YAML) settings. DDR upgrade is not enabled by default.

The remote Fedora 44 host has a package installed that is affected by multiple vulnerabilities as referenced in the FEDORA-2026-51cdd1292b advisory.

    Bug Fixes:

    CVE-2026-33254: An attacker can create a large number of concurrent DoQ or DoH3 connections, causing     unlimited memory allocation in DNSdist and leading to a denial of service. DOQ and DoH3 are disabled by     default

    CVE-2026-33257: An attacker can send a web request that causes unlimited memory allocation in the internal     web server, leading to a denial of service. The web server is disabled and restricted by an ACL by default

    CVE-2026-33260: An attacker can send a web request that causes unlimited memory allocation in the internal     web server, leading to a denial of service. The web server is disabled and restricted by an ACL by default

    CVE-2026-33593: A client can trigger a divide by zero error leading to crash by sending a crafted DNSCrypt     query

    CVE-2026-33595: A client can trigger excessive memory allocation by generating a lot of errors responses     over a single DoQ and DoH3 connection, as some resources were not properly released until the end of the     connection. DOQ and DoH3 are disabled by default

    CVE-2026-33596: A client might theoretically be able to cause a mismatch between queries sent to a backend     and the received responses by sending a flood of perfectly timed queries that are routed to a TCP-only or     DNS over TLS backend

    CVE-2026-33597: A crafted query containing an invalid DNS label can prevent the PRSD detection algorithm     executed via DynBlockRulesGroup:setSuffixMatchRule or DynBlockRulesGroup:setSuffixMatchRuleFFI from being     executed

    CVE-2026-33598: A cached crafted response can cause an out-of-bounds read if custom Lua code calls     getDomainListByAddress() or getAddressListByDomain() on a packet cache

    CVE-2026-33599: A rogue backend can send a crafted SVCB response to a Discovery of Designated Resolvers     request, when requested via either the autoUpgrade (Lua) option to newServer or auto_upgrade (YAML)     settings. DDR upgrade is not enabled by default

    CVE-2026-33602: A rogue backend can send a crafted UDP response with a query ID off by one related to the     maximum configured value, triggering an out-of-bounds write leading to a denial of service

    CVE-2026-33594: A client can trigger excessive memory allocation by generating a lot of queries that are     routed to an overloaded DoH backend, causing queries to accumulate into a buffer that will not be released     until the end of the connection. Outgoing DoH is disabled by default



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 Debian 13 host has a package installed that is affected by multiple vulnerabilities as referenced in the dsa-6235 advisory.

    - -------------------------------------------------------------------------     Debian Security Advisory DSA-6235-1                   security@debian.org     https://www.debian.org/security/                       Moritz Muehlenhoff     April 28, 2026                        https://www.debian.org/security/faq
    - -------------------------------------------------------------------------

    Package        : dnsdist     CVE ID         : CVE-2026-0396  CVE-2026-0397  CVE-2026-24028                      CVE-2026-24029 CVE-2026-24030 CVE-2026-27853                      CVE-2026-27854 CVE-2026-33254 CVE-2026-33257                      CVE-2026-33260 CVE-2026-33593 CVE-2026-33594                      CVE-2026-33595 CVE-2026-33596 CVE-2026-33597                      CVE-2026-33598 CVE-2026-33599 CVE-2026-33602

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

    For the stable distribution (trixie), these problems have been fixed in     version 1.9.14-0+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.

There are packages installed that are affected by multiple vulnerabilities referenced in the following CVEs:

  - A cached crafted response can cause an out-of-bounds read if custom Lua code calls
    getDomainListByAddress() or getAddressListByDomain() on a packet cache. (CVE-2026-33598)

  - An attacker might be able to inject HTML content into the internal web dashboard by sending crafted DNS
    queries to a DNSdist instance where domain-based dynamic rules have been enabled via either
    DynBlockRulesGroup:setSuffixMatchRule or DynBlockRulesGroup:setSuffixMatchRuleFFI. (CVE-2026-0396)

  - When the internal webserver is enabled (default is disabled), an attacker might be able to trick an
    administrator logged to the dashboard into visiting a malicious website and extract information about the
    running configuration from the dashboard. The root cause of the issue is a misconfiguration of the Cross-
    Origin Resource Sharing (CORS) policy. (CVE-2026-0397)

  - An attacker might be able to trigger an out-of-bounds read by sending a crafted DNS response packet, when
    custom Lua code uses newDNSPacketOverlay to parse DNS packets. The out-of-bounds read might trigger a
    crash, leading to a denial of service, or access unrelated memory, leading to potential information
    disclosure. (CVE-2026-24028)

  - When the early_acl_drop (earlyACLDrop in Lua) option is disabled (default is enabled) on a DNS over HTTPs
    frontend using the nghttp2 provider, the ACL check is skipped, allowing all clients to send DoH queries
    regardless of the configured ACL. (CVE-2026-24029)

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

  - A rogue backend can send a crafted SVCB response to a Discovery of Designated Resolvers request, when     requested via either the autoUpgrade (Lua) option to newServer or auto_upgrade (YAML) settings. DDR     upgrade is not enabled by default. (CVE-2026-33599)

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

ID	Name	Product	Family	Severity
321078	Fedora 44 : dnsdist (2026-51cdd1292b)	Nessus	Fedora Local Security Checks	critical
310797	Debian dsa-6235 : dnsdist - security update	Nessus	Debian Local Security Checks	critical
440772	Alpine: multiple dnsdist packages: security update to 2.0.4-r0	Tenable Cloud Security	Alpine Linux Local Security Checks	critical
440772	Alpine: multiple dnsdist packages: security update to 2.0.4-r0	Tenable Self-Hosted Container Security	Alpine Linux Local Security Checks	critical
309700	Linux Distros Unpatched Vulnerability : CVE-2026-33599	Nessus	Misc.	high

Detections

Analytics

CVE-2026-33599

high

Tenable Plugins

critical

critical

critical

critical

high