pdns-recursor vulnerabilities

UBUNTU-CVE-2026-85559

[Out-of-bounds read in Recursor findScopeZero]

UBUNTU-CVE-2026-85558

[Recursor retains closed TCP client addresses until process exit]

UBUNTU-CVE-2026-85557

[Single web client not doing TLS handshake monopolizes web access]

UBUNTU-CVE-2026-85556

[Missing OPT RR owner-name validation bypasses ECS hardening]

UBUNTU-CVE-2026-85555

[DNSSEC validation bypass and cache poisoning in PowerDNS Recursor via out-of-band NS resolution]

UBUNTU-CVE-2026-73206

[A crafted DNS packet can cause a denial of service decompressing the DNS names in the packet]

UBUNTU-CVE-2026-73205

[A malicious client can cause too many TCP connections in TIME_WAIT state]

UBUNTU-CVE-2026-52682

[A crafted DNS packet can cause increased memory and CPU consumption]

• Update to 5.2.13-0+deb13u1

RRSIGs with too few labels can lead to bypass of DNSSEC wildcard validation

RRSIGs with too few labels can lead to bypass of DNSSEC wildcard validation

• Update to 5.2.12-0+deb13u1

Wildcard CNAME proof validation bypass

The issue is a DNSSEC validation bypass where wildcard expansion proofs (NSEC/NSEC3 records) are accepted without signature validation when the wildcard answer is a CNAME or DNAME record.

• Update to 5.2.12-0+deb13u1

Prefetch Feature Allows Persistent Ghost Domain Cache Poisoning Attack

If the auth responds very slowly and the records expire in between, the capping of TTLs is not enforced for lack of data. This does not happen on regular resolve as then then the child records are used immediately if not expired and thus valid, or the records are expired, and in that case not used. So this case can only happen if almost expired records are used to refresh the authoritative NS records.

Spoofed answers can mark an authoritative non-EDNS capable

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.

• Update to 5.2.11-0+deb13u1

ZONEMD validation can be bypassed

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

• Update to 5.2.11-0+deb13u1

Missing input validation for catalog zones

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

• Update to 5.2.11-0+deb13u1

Insufficient input validation in ZoneToCache

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.

• Update to 5.2.11-0+deb13u1

Information about ECS zero scoped answers might leak to clients that use a specific ECS

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

• Update to 5.2.11-0+deb13u1

ZoneToCache can poison the cache

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

• Update to 5.2.11-0+deb13u1

Insufficient input validation of internal web server

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.

• Update to 5.2.11-0+deb13u1

Insufficient validation of cookie reply

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.

• Update to 5.2.9-0+deb13u1

Null pointer accces in aggressive NSEC(3) cache

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

• Update to 5.2.9-0+deb13u1