CVE-2026-18664Critical· 9.1▾ MidnightWhen 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 t…
▾ Midnight zone — Critical, or high with PoC / in-the-wild
impact 50.1 · likelihood 0.1 · exploitation 0
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Exploit-prediction probability, daily snapshots since Sep 8.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via NVD
Last analysed / modified upstream
0.3%
0.3% → 0.4%
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.
nsd >= 3.0.0, < 4.15.1Upgrade past the affected range:
nsd 4.15.1Connected by shared product, vendor, weakness, or advisory.
CVE-2026-101339High· 8.7A 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
CVE-2026-101341High· 8.7Tokens 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 poi…
CVE-2026-101337High· 8.7When base64 data is split up in pieces, of 3 character or less, tokens were incorrectly calculated to produce 0 bytes
CVE-2026-101338High· 8.7When 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
CVE-2026-18916High· 7.5Any remote client can crash a NSD serve child, by throttling the TCP receive window after a TCP query
CVE-2026-19401High· 7.5Any 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)