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.
Advisories

No advisories yet.

Fixes

Solution

This issue is fixed in 4.15.1 and all later versions.


Workaround

No workaround given by the vendor.

History

Wed, 26 Aug 2026 15:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Wed, 26 Aug 2026 08:45:00 +0000

Type Values Removed Values Added
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.
Title Wrong interpretation of ACL ranges
Weaknesses CWE-284
CWE-697
References
Metrics cvssV4_0

{'score': 8.2, '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'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: NLnet Labs

Published:

Updated: 2026-08-26T14:47:35.523Z

Reserved: 2026-08-03T13:23:02.012Z

Link: CVE-2026-18664

cve-icon Vulnrichment

Updated: 2026-08-26T14:47:19.371Z

cve-icon NVD

Status : Received

Published: 2026-08-26T09:16:45.437

Modified: 2026-08-26T15:16:46.153

Link: CVE-2026-18664

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-08-26T09:30:04Z

Weaknesses