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Vulnerability · Published Oct 14, 2026 · Assigned by NLnet Labs

CVE-2026-101337Stack overwrite from specially formatted base64 RDATA field

High 8.7

In plain English

A high-severity stack buffer overflow in NSD from NLnet Labs. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 28% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 4.0)8.7High
Exploit odds (30 days)0.3%top 72.3% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official 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).

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Alpine:v3.21nsd4.11.1-r1ALPINE-CVE-2026-101337
Alpine:v3.22nsd4.12.0-r1ALPINE-CVE-2026-101337
Alpine:v3.23nsd4.13.0-r1ALPINE-CVE-2026-101337
Alpine:v3.24nsd4.14.3-r1ALPINE-CVE-2026-101337
Debian:12nsdno fix listedDEBIAN-CVE-2026-101337
Debian:13nsdno fix listedDEBIAN-CVE-2026-101337
Debian:14nsd4.15.3-1DEBIAN-CVE-2026-101337
Ubuntu:26.10nsdno fix listedUBUNTU-CVE-2026-101337

Affected products (as reported)

VendorProductVersions
NLnet Labs NSD 4.10.0 – before 4.15.3

Weakness: CWE-121 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

References