CVE-2026-101338
High
Description
When a SVCB or HTTPS RR has filled the wire format RDATA up to the brim, another ECH parameter may overwrite the stack, and once beyond the limit, the base64 decoder can write attacker controlled data of unlimited size. 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).
SeverityHigh
CVSS8.7
Exploit probability—
ProductNSD
PublishedOct 14, 2026
First seenOct 14, 2026
Weakness typeCWE-121CWE-121
How to fix
Update
- NLnet Labs NSD4.15.3 or later
Vendor advisories
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| NLnet Labs NSD | 4.10.0 ≤ v < 4.15.3 | 4.15.3 |
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