Arbitrary Size Write Vulnerability in NSD by NLnet Labs

CVE-2026-101341

What is CVE-2026-101341?

The NSD DNS server from NLnet Labs is affected by a vulnerability that allows for arbitrary-sized out-of-bounds stack writes. Specifically, tokens of text in RDATA, such as those found in TXT records, that are less than 32 bytes are not subjected to checks ensuring they remain within their designated space. This oversight can lead to potential overwrites of critical components, including callback function pointers that are executed immediately after parsing. For affected NSD instances operating as secondary servers, zone files output by NSD will not exhibit this flaw. However, any zone file provided directly to NSD, especially from operator-controlled sources, may be susceptible to this vulnerability.

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