This fix provides extra hardening for the 5.4.x branch by doing extra validation of incoming answers from authoritative servers.

Spoofing replies to Recursor might mark an IP of an authoritative server as not supporting EDNS, causing valdiation of DNSSEC records served by that server to fail.

An invalid zone might pass ZONEMD validation while it should not. This is only relevant if ZoneToCache is configured with ZONEMD validation.

Incomplete validation of the SOA record present in a catalog zone might lead to a crash.

A malicious authoritative server can send a crafted zone via the ZoneToCache function that leads to a crash of the Recursor due to insuffcient input validation.

ECS zero scoped answers are stored in the packet cache while they should not. This impacts only configurations that have ECS enabled;

A malicious authoritative server can send a crafted zone via the ZoneToCache function that leads to cache poisoning.

An attacker can send a crafted EDNS OPT record that will be ignored by DNSdist’s filtering rules, but will be rewritten as a valid OPT record when EDNS Client Subnet is inserted, causing the backend to see the EDNS option(s) that DNSdist did not filter.

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.

An out-of-bounds read might happen when SetMacAddrAction is used, potentially resulting in uninitialized memory being sent over the network or a crash.

An attacker might be able to cause outgoing TCP connections to backend to be stuck until a timeout occurs instead of being released immediately, by sending IXFR queries. This could be used to cause a denial of service if there is a limit to the number of concurrent connections to this backend, or if the process runs out of file descriptors.

An attacker might be able to delay the processing of DoH3 queries by sending DoH3 GET queries with an invalid DATA frame.

An attacker sending a large number of crafted DNS queries might be able to trigger a dynamic block being inserted with a value causing invalid output to be produced in the prometheus endpoint. The prometheus endpoint will then be rejected by the scraper until the dynamic block expires.

An attacker can send a web request that causes unlimited memory allocation in the internal web server, leading to a denial of service. The internal web server is disabled by default.

Incorrect Behaviour of Views with TCP PROXY Requests

Concurrency and locking defects in GSS-TSIG

Insufficient Validation of Autoprimary SOA Queries

Insufficient Validation of Names During AXFR

Insufficient Validation of Member Zone Data May Cause Catalog Zone Transfer to Fail

An operator allowed to use the REST API can cause the Authoritative server to produce invalid HTTPS or SVCB record data, which can in turn cause LMDB database corruption, if using the LMDB backend.

A rogue primary server may cause file descriptor exhaustion and eventually a denial of service, when a PowerDNS secondary server forwards a DNS update request to it.

Incomplete escaping of LDAP queries when running with 8bit-dns enabled allows users to perform queries of internal domain subtrees.

An attacker can send a notify request that causes a new secondary domain to be added to the bind backend, but causes said backend to update its configuration to an invalid one, leading to the backend no longer able to run on the next restart, requiring manual operation to fix it.

A client can trigger a divide by zero error leading to crash by sending a crafted DNSCrypt query.

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.

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.

PRSD detection denial of service

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.

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

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.

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.

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.

An attacker can send replies that result in a null pointer dereference, caused by a missing consistency check and leading to a denial of service. Cookies are disabled by default.

A zone transition from NSEC to NSEC3 might trigger an internal inconsistency and cause a denial of service.

An attacker can send a web request that causes unlimited memory allocation in the internal web server, leading to a denial of service. The internal web server is disabled by default.

Having many concurrent transfers of the same RPZ can lead to inconsistent RPZ data, use after free and/or a crash of the recursor. Normally concurrent transfers of the same RPZ zone can only occur with a malfunctioning RPZ provider.

By publishing and querying a crafted zone an attacker can cause allocation of large entries in the negative and aggressive NSEC(3) caches.

An attacker can send a web request that causes unlimited memory allocation in the internal web server, leading to a denial of service. The internal web server is disabled by default.

An attacker can send a web request that causes unlimited memory allocation in the internal web server, leading to a denial of service. The internal web server is disabled by default.

If you use the zoneToCache function with a malicious authoritative server, an attacker can send a zone that result in a null pointer dereference, caused by a missing consistency check and leading to a denial of service.

An RPZ sent by a malicious authoritative server can result in a null pointer dereference, caused by a missing consistency check and leading to a denial of service.

An attacker might be able to trigger a use-after-free by sending crafted DNS queries to a DNSdist using the DNSQuestion:getEDNSOptions method in custom Lua code. In some cases DNSQuestion:getEDNSOptions might refer to a version of the DNS packet that has been modified, thus triggering a use-after-free and potentially a crash resulting in denial of service.

An attacker might be able to trigger an out-of-bounds write by sending crafted DNS responses to a DNSdist using the DNSQuestion:changeName or DNSResponse:changeName methods in custom Lua code. In some cases the rewritten packet might become larger than the initial response and even exceed 65535 bytes, potentially leading to a crash resulting in denial of service.

An attacker might be able to trick DNSdist into allocating too much memory while processing DNS over QUIC or DNS over HTTP/3 payloads, resulting in a denial of service. In setups with a large quantity of memory available this usually results in an exception and the QUIC connection is properly closed, but in some cases the system might enter an out-of-memory state instead and terminate the process.

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.

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.

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.

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.

Crafted delegations or IP fragments can poison cached delegations in Recursor.

Crafted delegations or IP fragments can poison cached delegations in Recursor.