{"id":"CVE-2026-18664","state":"PUBLISHED","title":"Wrong interpretation of ACL ranges","description":"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.","publishedAt":"2026-08-26T08:34:22.871Z","updatedAt":"2026-08-26T14:47:35.523Z","severity":{"score":8.2,"label":"High","version":"4.0","vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N","source":"NLnet Labs"},"assigner":"NLnet Labs","products":["NLnet Labs NSD"],"affected":[{"vendor":"NLnet Labs","product":"NSD","defaultStatus":"unaffected","versions":[{"version":"3.0.0","status":"affected","lessThan":"4.15.1","versionType":"semver"}]}],"references":["https://www.nlnetlabs.nl/downloads/nsd/CVE-2026-18664.txt"],"weaknesses":["CWE-284","CWE-697"],"ingestedAt":"2026-10-29T20:11:10.572Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/18xxx/CVE-2026-18664.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-18664","state":"PUBLISHED","datePublished":"2026-08-26T08:34:22.871Z","dateUpdated":"2026-08-26T14:47:35.523Z","assignerShortName":"NLnet Labs","assignerOrgId":"206fc3a0-e175-490b-9eaa-a5738056c9f6","dateReserved":"2026-08-03T13:23:02.012Z"},"containers":{"cna":{"title":"Wrong interpretation of ACL ranges","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"NLnet Labs","product":"NSD","defaultStatus":"unaffected","versions":[{"version":"3.0.0","status":"affected","lessThan":"4.15.1","versionType":"semver"}]}],"references":[{"url":"https://www.nlnetlabs.nl/downloads/nsd/CVE-2026-18664.txt","tags":["vendor-advisory"]}],"metrics":[{"format":"CVSS","scenarios":[{"lang":"en","value":"IP range access control restrictions can be bypassed for some unintended IP addresses on little endian systems"}],"cvssV4_0":{"version":"4.0","baseScore":8.2,"baseSeverity":"HIGH","vectorString":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-284","lang":"en","description":"CWE-284 Improper Access Control","type":"CWE"},{"cweId":"CWE-697","lang":"en","description":"CWE-697 Incorrect Comparison","type":"CWE"}]}],"providerMetadata":{"shortName":"NLnet Labs","orgId":"206fc3a0-e175-490b-9eaa-a5738056c9f6","dateUpdated":"2026-08-26T08:37:21.775Z"},"solutions":[{"lang":"en","value":"This issue is fixed in 4.15.1 and all later versions."}],"credits":[{"lang":"en","type":"finder","value":"Qifan Zhang from Palo Alto Networks"},{"lang":"en","type":"finder","value":"Claude and Ada Logics"}],"timeline":[{"time":"2026-07-13T21:35:01.000Z","lang":"en","value":"Issue reported by Qifan Zhang"},{"time":"2026-07-30T13:03:37.000Z","lang":"en","value":"NLnet Labs shares patch"},{"time":"2026-08-01T08:15:22.000Z","lang":"en","value":"Qifan Zhang verifies patch"},{"time":"2026-08-26T12:00:00.000Z","lang":"en","value":"Issue reported by Claude and Ada Logics"},{"time":"2026-08-26T12:00:00.000Z","lang":"en","value":"Fix released with version 4.15.1"}],"datePublic":"2026-08-26T12:00:00.000Z","x_generator":{"engine":"cvelib 1.8.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-08-26T14:33:17.602462Z","id":"CVE-2026-18664","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-08-26T14:47:35.523Z"}}]}}}