CVE-2026-18664 Affecting nsd package, versions <4.15.1-1
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-DEBIANUNSTABLE-NSD-19425057
- published29 Aug 2026
- disclosed26 Aug 2026
Introduced: 26 Aug 2026
NewCVE-2026-18664 (opens in a new tab)How to fix?
Upgrade Debian:unstable nsd to version 4.15.1-1 or higher.
NVD Description
Note: Versions mentioned in the description apply only to the upstream nsd package and not the nsd package as distributed by Debian.
See How to fix? for Debian:unstable relevant fixed versions and status.
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.