CVE-2026-18664Wrong interpretation of ACL ranges
Updated under an hour ago ()
Does this affect you?
It affects NLnet Labs NSD and 1 other product. Add what you run to find out whether that includes you.
No exploitation reported and no EPSS estimate yet.
Do this next
Free account, 1 product
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.
- CVSS
- 8.2 HIGH (v4.0, CNA)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
- Weakness (CWE)
- CWE-284, CWE-697
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- NLnet Labs
- NVD analysis
- Analyzed
- Record last updated
- Aug 26, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
NLnet Labs NSD nlnet_labs:nsd (from the name) | from 3.0.0 before 4.15.1 | CNA record |
nlnetlabs nsd nlnetlabs:nsd | from 3.0.0 before 4.15.1 | NVD |
References
- https://www.nlnetlabs.nl/downloads/nsd/CVE-2026-18664.txtvendor-advisory
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.