[dnsdist] PowerDNS DNSdist 1.9.13 and 2.0.4 Released (Security Release)

[Remi Gacogne]

Hi,

Today we released two new versions of DNSdist, 1.9.13 and 2.0.4, fixing 
several security issues that have been reported to us. These security 
issues are medium to high severity, and we recommend upgrading quickly.

The issues fixed in these releases are:
- 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. DNSCrypt is disabled by default
- 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
- 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

The complete list of changes can be found in the ChangeLogs [1][2]. 
Please see the DNSdist website [3] for the current documentation. The 
upgrade guide is also available there [4]. The full security advisory 
[5] can be found on our website as well.

Please send us all feedback and issues you might have via the mailing 
list, or in case of a bug, via GitHub [6].

The release tarballs [7][8] and their signatures [9][10] are available 
on the downloads website, and packages for several distributions are 
available from our repository [11].

[1]: https://dnsdist.org/changelog.html#change-1.9.13
[2]: https://dnsdist.org/changelog.html#change-2.0.4
[3]: https://dnsdist.org
[4]: https://dnsdist.org/upgrade_guide.html
[5]: 
https://www.dnsdist.org/security-advisories/powerdns-advisory-for-dnsdist-2026-04.html
[6]: https://github.com/PowerDNS/pdns/issues/new/choose
[7]: https://downloads.powerdns.com/releases/dnsdist-1.9.13.tar.bz2
[8]: https://downloads.powerdns.com/releases/dnsdist-1.9.13.tar.bz2.sig
[9]: https://downloads.powerdns.com/releases/dnsdist-2.0.4.tar.xz
[10]: https://downloads.powerdns.com/releases/dnsdist-2.0.4.tar.xz.sig
[11]: https://repo.powerdns.com

Best regards,
-
Remi Gacogne
PowerDNS.COM BV - https://www.powerdns.com/

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