unbound: Unbound: Denial of Service via terminated DNS-over-QUIC queries

A flaw was found in Unbound, a Domain Name System DNS resolver. A remote attacker can exploit this vulnerability by sending and immediately terminating DNS-over-QUIC DoQ queries. This improper handling of terminated queries can lead to a build-up of pending responses, causing a degradation of...

CVE-2026-55991

CVE-2026-55991 affects NLnet Labs Unbound 1.22.0–1.25.1. A remote unauthenticated DoQ client can trigger a libngtcp2 assertion by passing an erroneous error value when ngtcp2_conn_writev_stream() returns NGTCP2_ERR_STREAM_DATA_BLOCKED and Unbound calls ngtcp2_ccerr_set_application_error() with -1...

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

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-2026-41637 Degradation of resolution service from improperly accounted client-terminated DNS-over-QUIC queries

In NLnet Labs Unbound 1.22.0 up to and including 1.25.1, client terminated DNS-over-QUIC DoQ queries are not accounted properly by Unbound resulting in low-cost inflation of the waiting number of replies for already in-flight resolution queries. This results in degradation of resolution service f...

CVE-2026-41637

In NLnet Labs Unbound 1.22.0 up to and including 1.25.1, client terminated DNS-over-QUIC DoQ queries are not accounted properly by Unbound resulting in low-cost inflation of the waiting number of replies for already in-flight resolution queries. This results in degradation of resolution service f...

CVE-2026-41637

CVE-2026-41637 affects NLnet Labs Unbound (versions 1.22.0 to 1.25.1). The vulnerability arises when client-terminated DNS-over-QUIC (DoQ) queries are not counted properly, allowing a low-cost inflation of the waiting queue for in-flight queries and causing degradation of resolution service for n...

EUVD-2026-47665

In NLnet Labs Unbound 1.22.0 up to and including 1.25.1, client terminated DNS-over-QUIC DoQ queries are not accounted properly by Unbound resulting in low-cost inflation of the waiting number of replies for already in-flight resolution queries. This results in degradation of resolution service f...

CVE-2026-41637 Degradation of resolution service from improperly accounted client-terminated DNS-over-QUIC queries

In NLnet Labs Unbound 1.22.0 up to and including 1.25.1, client terminated DNS-over-QUIC DoQ queries are not accounted properly by Unbound resulting in low-cost inflation of the waiting number of replies for already in-flight resolution queries. This results in degradation of resolution service f...

CVE-2026-32665 Remote DNS-over-QUIC denial of service due to `quic-size` budget bypass

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...

EUVD-2026-47663

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...

CVE-2026-32665

Unbound 1.22.0–1.25.1 with downstream DNS-over-QUIC enabled is vulnerable. The first two QUIC streams on a new connection (streams 0 and 4) bypass the per-stream quic-size gate, causing large input buffers to be allocated after only the 2-byte length prefix. A remote attacker can force Unbound to...

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...

CVE-2026-32665 Remote DNS-over-QUIC denial of service due to `quic-size` budget bypass

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...

CVE-2026-14586 Assertion in libngtcp2 when under pressure in high concurrency DNS-over-QUIC environments

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...

CVE-2026-14586

CVE-2026-14586 affects NLnet Labs Unbound 1.22.0–1.25.1 in DNS-over-QUIC (DoQ) environments under high concurrency. The root cause is an assertion in libngtcp2 related to monotonic timestamps; Unbound used realtime, which can trigger an assertion in libngtcp2 for the QUIC timestamp, potentially t...

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...

CVE-2026-16318

A flaw was found in s2n-tls, a Transport Layer Security TLS implementation. An unauthenticated remote attacker can exploit a memory leak in the QUIC transport parameters extension handler. By repeatedly forcing HelloRetryRequests during a TLS 1.3 connection, an attacker can cause the server proce...

Missing Release of Memory after Effective Lifetime

Overview Affected versions of this package are vulnerable to Missing Release of Memory after Effective Lifetime in the QUIC transport parameters extension handler during the processing of HelloRetryRequest messages. An attacker can cause increased memory consumption by repeatedly triggering...