CVE-2026-101337
NSD: Stack overwrite from specially formatted base64 RDATA field
NLnet Labs NSD
CVSS
8.7HighExploitationNo known exploitationNot in CISA KEV, which does not prove it is unexploitedCISA KEV
Exploit odds (EPSS)0.32%Chance of exploitation activity in the next 30 days, higher than 23% of CVEs. Scored 23 Oct 2026FIRST EPSS
What fixes it
- 4.15.3NSDCVE List
A fixed version on one release line is not the upgrade target for every line. Check your exact version and any vendor backports.
Description
When base64 data is split up in pieces, of 3 character or less, tokens were incorrectly calculated to produce 0 bytes. This enables attackers to overwrite the stack with up to 64K of attacker controlled data. Zone files which are written out by NSD itself, such as for zones for which the NSD instance is secondary, will not be formatted like this. The zone file must be fed to NSD directly, (but it could come, for example, from an operator controlled provisioning system).
Text from CVE List
Affected versions 1
- NSDaffected: 4.10.0 before 4.15.3CVE List