Nlnet Labs Nsd vulnerabilities

CVE-2026-12244 [HIGH] CWE-122 CVE-2026-12244: If NSD is configured as secondary for a zone, the primary of that zone can crash NSD with an AXFR co If NSD is configured as secondary for a zone, the primary of that zone can crash NSD with an AXFR containing a DNS message with a special crafted SVCB RR with an rdata size of 65512, that let's an (uint16_t) variable that is used to allocate space needed for the RR wrap (because total size > 65535), causing a heap overflow. The attacker can perform a

CVE-2026-18664 [CRITICAL] CWE-284 CVE-2026-18664: When ranges are used for access control (i.e. of the form 1.2.3.4-1.2.3.25), because NSD wrongly com When ranges are used for access control (i.e. of the form 1.2.3.4-1.2.3.25), because NSD wrongly compares the IP address with the range on little endian systems, IPs that were meant to be allowed may be denied, and, IPs that were meant to be denied access could be allowed. An IPv4 address is compared with IPv4 ranges as unsigned 32 bit numbers dir

CVE-2026-12246 [HIGH] CWE-20 CVE-2026-12246: NSD version 4.14.0 introduced a bug where a specially crafted APL RR, with an adflength larger than NSD version 4.14.0 introduced a bug where a specially crafted APL RR, with an adflength larger than permitted for the address family will overwrite the stack when the zone is written to disk, with a maximum of 111 attacker controlled bytes.

CVE-2026-19538 [HIGH] CWE-290 CVE-2026-19538: The BLOCKED access control list items that are evaluated to deny access on the the proxy protocol po The BLOCKED access control list items that are evaluated to deny access on the the proxy protocol port can be bypassed completely when connecting over TCP or TLS and sending the query twice on connection that is kept open.

CVE-2026-18916 [HIGH] CWE-191 CVE-2026-18916: Any remote client can crash a NSD serve child, by throttling the TCP receive window after a TCP quer Any remote client can crash a NSD serve child, by throttling the TCP receive window after a TCP query. By continuously crashing the serve childs, the remote client can denial all TCP service to this NSD instance.

CVE-2026-12490 [HIGH] CWE-284 CVE-2026-12490: When a provide-xfr is given with a tls-auth-name, a secondary requesting a transfer should provide a When a provide-xfr is given with a tls-auth-name, a secondary requesting a transfer should provide a client certificate with that name. However, no client certificate is needed when the request comes in over TLS over the regular tls-port (and not the tls-auth-port) or over over TCP over the regular port, when the other conditions of the provide-xfr ru

CVE-2026-19401 [HIGH] CWE-400 CVE-2026-19401: Any remote client can crash a (debugging/non-release build type) NSD serve child by sending it a spe Any remote client can crash a (debugging/non-release build type) NSD serve child by sending it a special crafted message with a specially tuned number of DNS Cookie options (17 when UDP payload size is 512). By continuously crashing the serve childs, the remote client can severely hamper or, when positioned sufficiently close, deny all DNS service.

CVE-2026-12245 [HIGH] CWE-416 CVE-2026-12245: NSD from version 4.13.0 has a heap use-after-free bug in logging errors on TLS connections, causing NSD from version 4.13.0 has a heap use-after-free bug in logging errors on TLS connections, causing a crash of the server process, which can be triggered trivially by sending a DNS query over a DoT connection, and closing the connection without reading the response.

CVE-2020-28935 [MEDIUM] CWE-59 CVE-2020-28935: NLnet Labs Unbound, up to and including version 1.12.0, and NLnet Labs NSD, up to and including vers NLnet Labs Unbound, up to and including version 1.12.0, and NLnet Labs NSD, up to and including version 4.3.3, contain a local vulnerability that would allow for a local symlink attack. When writing the PID file, Unbound and NSD create the file if it is not there, or open an existing file for writing. In case the file was already present, they would