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nsd vulnerabilities

Vulnerabilities published for nsd in the last 30 days: 4. Listed in the KEV catalogue: 0.

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Vulnerabilities: 13

  1. CVE-2026-101341

    High · CVSS 8.7EPSS 0.34%No fix published

    Stack overwrite from specially formatted TXT-DATA RDATA field

    Tokens of text in RDATA (of for example TXT records) under 32 bytes are not checked to stay within the space reserved for the RDATA allowing for arbitrary sized out of bound stack writes, including an overwrite of a callback function pointer which is called directly after parse. Zone files which are written out by NSD itself, such for zones for which the NSD instance is secondary, will not be formatted like this. The zone file must be fed to NSD directly, (but it could come, for example, from an operator controlled provisioning system).

    nsdOperating systems
    Published Updated
    Source advisory 1 ↗Source advisory 2 ↗

  2. CVE-2026-101339

    High · CVSS 8.7EPSS 0.32%No fix published

    Stack overwrite from a specially crafted and formatted HIP RR

    A HIP resource record that fills the RDATA near or at is limit, and has another dname RDATA field (a HIP Rendezvous server) can overwrite the stack with up to 191 bytes of attacker controlled data. Zone files which are written out by NSD itself, such as for zones for which the NSD instance is secondary, will not be formatted like this. The zone file must be fed to NSD directly, (but it could come, for example, from an operator controlled provisioning system).

    nsdOperating systems
    Published Updated
    Source advisory 1 ↗Source advisory 2 ↗

  3. CVE-2026-101338

    High · CVSS 8.7EPSS 0.32%No fix published

    Stack overwrite from a specially crafted and formatted SVCB or HTTPS RR

    When a SVCB or HTTPS RR has filled the wire format RDATA up to the brim, another ECH parameter may overwrite the stack, and once beyond the limit, the base64 decoder can write attacker controlled data of unlimited size. Zone files which are written out by NSD itself, such as for zones for which the NSD instance is secondary, will not be formatted like this. The zone file must be fed to NSD directly, (but it could come, for example, from an operator controlled provisioning system).

    nsdOperating systems
    Published Updated
    Source advisory 1 ↗Source advisory 2 ↗

  4. CVE-2026-101337

    High · CVSS 8.7EPSS 0.32%No fix published

    Stack overwrite from specially formatted base64 RDATA field

    When base64 data is split up in pieces, of 3 character or less, tokens were incorrectly calculated to produce 0 bytes. This enables attackers to overwrite the stack with up to 64K of attacker controlled data. Zone files which are written out by NSD itself, such as for zones for which the NSD instance is secondary, will not be formatted like this. The zone file must be fed to NSD directly, (but it could come, for example, from an operator controlled provisioning system).

    nsdOperating systems
    Published Updated
    Source advisory 1 ↗Source advisory 2 ↗

  5. CVE-2026-19538

    High · CVSS 8.2EPSS 0.26%No fix published

    Bypass of BLOCKED ACL items on proxy protocol port over TCP or TLS

    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.

    nsdOperating systems
    Published Updated
    Source advisory 1 ↗Source advisory 2 ↗

  6. CVE-2026-19401

    High · CVSS 8.2EPSS 0.28%No fix published

    Remote UDP DoS by sending multiple DNS Cookie options

    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.

    nsdOperating systems
    Published Updated
    Source advisory 1 ↗Source advisory 2 ↗

  7. CVE-2026-18916

    Medium · CVSS 6.9EPSS 0.28%No fix published

    Remote TCP DoS by throttling the TCP receive window

    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.

    nsdOperating systems
    Published Updated
    Source advisory 1 ↗Source advisory 2 ↗

  8. CVE-2026-18664

    High · CVSS 8.2EPSS 0.26%No fix published

    Wrong interpretation of ACL ranges

    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 directly with the endianness of the host, but the values to compare are in network byte order (big-endian). With IPv6 addresses the comparison is done in 4 times a unsigned 32 bit number comparison, again with the endianness of the host where all values are actually in network bye order.

    nsdOperating systems
    Published Updated
    Source advisory 1 ↗Source advisory 2 ↗

  9. CVE-2026-12490

    High · CVSS 8.2EPSS 0.22%No fix published

    Bypass of client certificate verification with transfer over TLS

    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 rule match.

    nsdOperating systems
    Published Updated
    Source advisory 1 ↗Source advisory 2 ↗

  10. CVE-2026-12246

    High · CVSS 7.2EPSS 0.44%No fix published

    Out of bounds stack write with crafted APL RR

    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.

    nsdOperating systems
    Published Updated
    Source advisory 1 ↗Source advisory 2 ↗

  11. CVE-2026-12245

    High · CVSS 8.7EPSS 0.46%No fix published

    Denial of DNS over TLS service by any DoT client

    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.

    nsdOperating systems
    Published Updated
    Source advisory 1 ↗Source advisory 2 ↗

  12. CVE-2026-12244

    High · CVSS 8.7EPSS 0.49%No fix published

    Heap overflow and crash with crafted SVCB RR

    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 controlled (RCE class) head write of up to 65509 bytes

    nsdOperating systems
    Published Updated
    Source advisory 1 ↗Source advisory 2 ↗

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