CVE-2026-56416 Possible heap buffer overflow when validator canonicalizes RDATA that contains domain name

In NLnet Labs Unbound up to and including version 1.25.1, when the validator builds the canonical RDATA form for an RRSIG-covered PX/RP/MINFO/SOA RRset, it computes the address of the second embedded domain name as 'datstart + dnamevaliddatstart, ...' and passes it straight to 'querydnametolower'...

unbound: Unbound DNSSEC Validator Use-After-Free via Deep Copy Pointer Overwrite Leading to DoS and Possible Remote Code Execution

A flaw was discovered in Unbound’s DNSSEC validator can leave it using an invalid memory pointer after certain DS sub-query validations fail due to NSEC3 budget exhaustion. This may cause crashes and could potentially allow arbitrary code execution...

CVE-2026-42959

A flaw was found in Unbound's DNSSEC validator when constructing chase-reply messages for validation. The code uses the wrong counter to calculate write offsets for ADDITIONAL section resource record sets. When a DNAME chain is combined with authority filtering, an uninitialized array slot is...

CVE-2026-33278

A flaw was discovered in Unbound’s DNSSEC validator can leave it using an invalid memory pointer after certain DS sub-query validations fail due to NSEC3 budget exhaustion. This may cause crashes and could potentially allow arbitrary code execution...

CVE-2026-33278 Possible arbitrary code execution during DNSSEC validation

NLnet Labs Unbound 1.19.1 up to and including version 1.25.0 has a vulnerability in the DNSSEC validator that enables denial of service and possible remote code execution as a result of deep copying a data structure and erroneously overwriting a destination pointer. An adversary can exploit the...

PT-2026-42125

Name of the Vulnerable Software and Affected Versions NLnet Labs Unbound versions 1.19.1 through 1.25.0 Description A flaw in the DNSSEC validator allows for denial of service and potential remote code execution. The issue occurs during the deep copying of a data structure when DS sub-queries...