UBUNTU-CVE-2026-40691

In Unbound 1.9.0 up to and including 1.25.1, when a DNSCrypt query is received over TCP, the routine that encrypts the reply in place fails to bound the reply length against the destination buffer size. The size clamp that protects the UDP path is not applied on the TCP path, so a reply larger th...

UBUNTU-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...

UBUNTU-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'...

UBUNTU-CVE-2026-44690

In NLnet Labs Unbound 1.7.0 up to and including 1.25.1, insufficient validation of the RRSIG.Labels field combined with premature cache writes during RFC 8198 aggressive NSEC processing leads to cache poisoning that permits a malicious actor controlling a single delegated zone to poison arbitrary...

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-2026-50248

In NLnet Labs Unbound 1.7.0 up to and including 1.25.1, when an auth/rpz zone has a configured primary hostname that resolves to BOGUS A/AAAA, it is still considered as a possible XFR endpoint. A malicious actor that can spoof the hostname's A/AAAA record no valid RRSIG required becomes the zone'...

CVE-2026-55990

In NLnet Labs Unbound 1.7.0 up to and including 1.25.1, when the 'dnscrypt:' clause lists more 'dnscrypt-provider-cert:' files than there are matching 'dnscrypt-secret-key:' files, Unbound fills only the matched prefix and leaves the tail slots at the '0xdb' fill that libsodium's allocator writes...

CVE-2026-50046

In NLnet Labs Unbound 1.15.0 up to and including 1.25.1, the TLS server name used for DNS-over-TLS DoT forwarded queries is tied to a struct's 'servicedquery' lifetime but also referenced by another struct 'waitingtcp'. When the owning struct is jostled out of the mesh while the DoT TCP stream is...

UBUNTU-CVE-2026-52863

In NLnet Labs Unbound 1.25.0 up to and including 1.25.1, a fix that makes the 'respip' and 'dns64' modules work together, creates a shallow copy of the view name in effect that could lead to memory corruption if the owner of the original view name is jostled out when Unbound is under pressure...

UBUNTU-CVE-2026-50045

In NLnet Labs Unbound 1.22.0 up to and including 1.25.1, a single client query for a deeply nested name under a DNSSEC-signed parent can cause Unbound to send more upstream packets per client query than the configured 'max-global-quota'. This effectively bypasses a security configuration that...

UBUNTU-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...

UBUNTU-CVE-2026-32665

In NLnet Labs Unbound 1.22.0 up to and including 1.25.1, when downstream DNS-over-QUIC DoQ is enabled, the first two bidirectional streams on a new QUIC connection streamid 0 and 4 bypass the per-stream 'quic-size' gate entirely, and large input buffers are allocated later, after only the 2-byte...

UBUNTU-CVE-2026-44687

In NLnet Labs Unbound 1.13.2 up to and including 1.25.1, stub or forward zones where the name is below an intermediate labed below a DNSSEC signed zone could be shadowed by the intermediate label's secure NXDOMAIN answer from the parent. This is caused by an off-by-one error in...

UBUNTU-CVE-2026-50251

In NLnet Labs Unbound up to and including version 1.25.1, when 'unwanted-reply-threshold' is enabled set to any value greater than zero, glue records of 0.0.0.0/::0 can short-circuit Unbound, on systems that can direct such traffic, by issuing DNS queries and receiving seemingly unwanted replies...

CVE-2026-50045

In NLnet Labs Unbound 1.22.0 up to and including 1.25.1, a single client query for a deeply nested name under a DNSSEC-signed parent can cause Unbound to send more upstream packets per client query than the configured 'max-global-quota'. This effectively bypasses a security configuration that...

UBUNTU-CVE-2026-55717

In NLnet Labs Unbound 1.10.0 up to and including 1.25.1, when 'serve-expired: yes' is set together with a 'response-ip: redirect' /'response-ip-data: CNAME ' rule or the RPZ 'rpz-cname-override' equivalent, a remote client who controls any delegated domain can crash the daemon. The...

UBUNTU-CVE-2026-14586

In NLnet Labs Unbound 1.22.0 up to and including 1.25.1, in DNS-over-QUIC environments, with high concurrency and under pressure, an assertion in libngtcp2 about monotonic timestamps could trigger and result in server termination and thus denial of service. When interfacing with libngtcp2, for...

UBUNTU-CVE-2026-54478

In NLnet Labs Unbound 1.18.0 up to and including 1.25.1, when Unbound listens on a 'proxy-protocol-port' interface with 'answer-cookie: yes', the RFC 9018 server-cookie SipHash is computed over the proxy's wire address instead of the PROXYv2-declared client. One server cookie obtained through a...

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...

unbound: Unbound: Denial of Service via assertion failure in DNS-over-QUIC environments

A flaw was found in Unbound. Under heavy DNS-over-QUIC DoQ traffic, a timing discrepancy in Unbound’s libngtcp2 library can trigger an assertion failure. This causes the server to crash unexpectedly, resulting in a denial of service DoS...