unbound: Unbound: Denial of Service via DNSSEC query amplification bypass

A vulnerability in Unbound allows a remote attacker to bypass upstream amplification limits by querying a deeply nested name under a DNSSEC-signed parent. This triggers excessive outbound traffic per query, potentially causing a denial of service DoS...

unbound: Unbound: Denial of Service due to freed pointer dereference in DNS-over-TLS handling

A use-after-free flaw was found in Unbound's DNS-over-TLS DoT forwarded query handling. A remote attacker can exploit a timing error during TLS handshake failures on a server under load to trigger a daemon crash, resulting in a Denial of Service DoS...

CVE-2026-56444 Degradation of resolution service when 'discard-timeout' and 'serve-expired-client-timeout' are combined in unusual configuration

In NLnet Labs Unbound 1.20.0 up to and including 1.25.1, when Unbound is configured with 'serve-expired: yes' and 'serve-expired-client-timeout discard-timeout 0' contrary to the suggested values, the discard-timeout branch during the serve expired logic drops an aged client reply without...

CVE-2026-56444

CVE-2026-56444 affects NLnet Labs Unbound 1.20.0 through 1.25.1. When configured with serve-expired: yes and serve-expired-client-timeout > discard-timeout > 0, the discard-timeout branch in the serve-expired logic fails to decrement the counter for aged client replies, unlike other branche...

EUVD-2026-47685

In NLnet Labs Unbound 1.20.0 up to and including 1.25.1, when Unbound is configured with 'serve-expired: yes' and 'serve-expired-client-timeout discard-timeout 0' contrary to the suggested values, the discard-timeout branch during the serve expired logic drops an aged client reply without...

CVE-2026-56444

In NLnet Labs Unbound 1.20.0 up to and including 1.25.1, when Unbound is configured with 'serve-expired: yes' and 'serve-expired-client-timeout discard-timeout 0' contrary to the suggested values, the discard-timeout branch during the serve expired logic drops an aged client reply without...

CVE-2026-56444

In NLnet Labs Unbound 1.20.0 up to and including 1.25.1, when Unbound is configured with 'serve-expired: yes' and 'serve-expired-client-timeout discard-timeout 0' contrary to the suggested values, the discard-timeout branch during the serve expired logic drops an aged client reply without...

CVE-2026-56444 Degradation of resolution service when 'discard-timeout' and 'serve-expired-client-timeout' are combined in unusual configuration

In NLnet Labs Unbound 1.20.0 up to and including 1.25.1, when Unbound is configured with 'serve-expired: yes' and 'serve-expired-client-timeout discard-timeout 0' contrary to the suggested values, the discard-timeout branch during the serve expired logic drops an aged client reply without...

CVE-2026-56444

In NLnet Labs Unbound 1.20.0 up to and including 1.25.1, when Unbound is configured with 'serve-expired: yes' and 'serve-expired-client-timeout discard-timeout 0' contrary to the suggested values, the discard-timeout branch during the serve expired logic drops an aged client reply without...

CVE-2026-56416

Technical details required to assess impact are not publicly available in the provided documents. No additional specifics (versions beyond 1.25.1, exploitation paths, or fixes) are included. Monitor for updates.

CVE-2026-56416

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'...

CVE-2026-56416

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'...

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'...

CVE-2026-56416

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'...

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'...

CVE-2026-55991

In NLnet Labs Unbound 1.22.0 up to and including 1.25.1, a remote unauthenticated client can trigger a libngtcp2 assertion if compiled with assertions on and terminate the entire Unbound process using a single DNS-over-QUIC DoQ connection and one normal DNS query. This is caused by an erroneous...

CVE-2026-55991 Remote DNS-over-QUIC (DoQ) flow-control assertion failure in libngtcp2

In NLnet Labs Unbound 1.22.0 up to and including 1.25.1, a remote unauthenticated client can trigger a libngtcp2 assertion if compiled with assertions on and terminate the entire Unbound process using a single DNS-over-QUIC DoQ connection and one normal DNS query. This is caused by an erroneous...

CVE-2026-55991 Remote DNS-over-QUIC (DoQ) flow-control assertion failure in libngtcp2

In NLnet Labs Unbound 1.22.0 up to and including 1.25.1, a remote unauthenticated client can trigger a libngtcp2 assertion if compiled with assertions on and terminate the entire Unbound process using a single DNS-over-QUIC DoQ connection and one normal DNS query. This is caused by an erroneous...

EUVD-2026-47683

In NLnet Labs Unbound 1.22.0 up to and including 1.25.1, a remote unauthenticated client can trigger a libngtcp2 assertion if compiled with assertions on and terminate the entire Unbound process using a single DNS-over-QUIC DoQ connection and one normal DNS query. This is caused by an erroneous...

CVE-2026-55991

In NLnet Labs Unbound 1.22.0 up to and including 1.25.1, a remote unauthenticated client can trigger a libngtcp2 assertion if compiled with assertions on and terminate the entire Unbound process using a single DNS-over-QUIC DoQ connection and one normal DNS query. This is caused by an erroneous...