NLnet Labs NSD up to 4.15.0 access control

Summaryinfo

A vulnerability classified as very critical has been found in NLnet Labs NSD up to 4.15.0. This impacts an unknown function. The manipulation leads to access control. This vulnerability is listed as CVE-2026-18664. The attack may be initiated remotely. There is no available exploit.

Detailsinfo

A vulnerability, which was classified as very critical, has been found in NLnet Labs NSD up to 4.15.0. This issue affects some unknown processing. The manipulation with an unknown input leads to a access control vulnerability. Using CWE to declare the problem leads to CWE-284. The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

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.

It is possible to read the advisory at nlnetlabs.nl. The identification of this vulnerability is CVE-2026-18664 since 08/03/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 08/26/2026). The attack technique deployed by this issue is T1068 according to MITRE ATT&CK.

Upgrading to version 4.15.1 eliminates this vulnerability.

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Type

• Domain Name Software

Vendor

• NLnet Labs

Name

• NSD

Version

• 4.0
• 4.1
• 4.2
• 4.3
• 4.4
• 4.5
• 4.6
• 4.7
• 4.8
• 4.9
• 4.10
• 4.11
• 4.12
• 4.13
• 4.14
• 4.15.0

CPE 2.3info

• 🔒
• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒
• 🔒

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CVSSv3info

CVSSv2info

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Entryinfo

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