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 (stream_id 0 and 4) bypass the per-stream 'quic-size' gate entirely, and large input buffers are allocated later, after only the 2-byte length prefix has been received from the initial streams. As a result, a remote client can make Unbound exceed the configured 'quic-size' limit with low-cost input. Using only one connection and two streams, each sending a declared 65535-byte length prefix and then holding the streams open, a client can already trivially make Unbound roughly allocate double that amount. This is a remote availability issue / memory-accounting bypass in the downstream DoQ implementation that leads to denial of service for new DoQ clients. This vulnerability needs Unbound to be compiled with DoQ support ('--with-libngtcp2') and the 'quic-port' to be configured for the listening interfaces.

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 (stream_id 0 and 4) bypass the per-stream 'quic-size' gate entirely, and large input buffers are allocated later, after only the 2-byte length prefix has been received from the initial streams. As a result, a remote client can make Unbound exceed the configured 'quic-size' limit with low-cost input. Using only one connection and two streams, each sending a declared 65535-byte length prefix and then holding the streams open, a client can already trivially make Unbound roughly allocate double that amount. This is a remote availability issue / memory-accounting bypass in the downstream DoQ implementation that leads to denial of service for new DoQ clients. This vulnerability needs Unbound to be compiled with DoQ support ('--with-libngtcp2') and the 'quic-port' to be configured for the listening interfaces.

libunbound8-1.25.2-1.1 on GA media

unbound: Unbound: Denial of Service via assertion failure in DNS-over-QUIC environments unbound: Unbound: Denial of Service via improper validation of DNS-over-QUIC client length unbound: Unbound: Denial of Service via crafted DNSCrypt query unbound: Unbound: Denial of Service via terminated DNS-over-QUIC queries unbound: Unbound: DNS cache integrity issue unbound: Unbound: Denial of Service due to 'harden-below-nxdomain' logic bypass unbound: Unbound: Cache poisoning via insufficient RRSIG.Labels validation and premature cache writes unbound: Unbound: Information disclosure via DNSSEC wildcard replay unbound: Unbound: Denial of Service via DNSSEC query amplification bypass unbound: Unbound: Denial of Service due to freed pointer dereference in DNS-over-TLS handling unbound: Unbound: Insecure DNS redirection via spoofed DNS answers unbound: Unbound: DNS response policy replacement via hostname spoofing unbound: NLnet Labs Unbound: Denial of Service via crafted DNS glue records unbound: Unbound: DNS cache poisoning via UDP source port predictability unbound: Unbound: Denial of service due to memory corruption under specific configurations. unbound: Unbound: DNS Cookie security bypass via incorrect server cookie calculation unbound: Unbound: Information disclosure due to local policy bypass via unbound-control unbound: Unbound: Denial of Service via crafted DNS responses with expired records unbound: Unbound: Denial of Service via malformed EDNS Report-Channel option unbound:…

Security update for unbound

Affected: Ubuntu:Pro:14.04:LTS: unbound, Ubuntu:Pro:16.04:LTS: unbound, Ubuntu:Pro:18.04:LTS: unbound, Ubuntu:Pro:20.04:LTS: unbound, Ubuntu:22.04:LTS: unbound, Ubuntu:24.04:LTS: unbound, Ubuntu:26.04:LTS: unbound

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 (stream_id 0 and 4) bypass the per-stream 'quic-size' gate entirely, and large input buffers are allocated later, after only the 2-byte length prefix has been received from the initial streams. As a result, a remote client can make Unbound exceed the configured 'quic-size' limit with low-cost input. Using only one connection and two streams, each sending a declared 65535-byte length prefix and then holding the streams open, a client can already trivially make Unbound roughly allocate double that amount. This is a remote availability issue / memory-accounting bypass in the downstream DoQ implementation that leads to denial of service for new DoQ clients. This vulnerability needs Unbound to be compiled with DoQ support ('--with-libngtcp2') and the 'quic-port' to be configured for the listening interfaces.

Ein Angreifer kann mehrere Schwachstellen in Unbound ausnutzen, um einen Denial of Service Angriff durchzuführen, um Informationen offenzulegen, um Daten zu manipulieren, und um Sicherheitsvorkehrungen zu umgehen.