What’s Vulnerable › Vulnerabilities
CVE-2026-101338: Stack overwrite from a specially crafted and formatted SVCB or HTTPS RR
- Severity: high (CVSS 8.7 v4.0)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 0.3% probability of exploitation in the next 30 days
- Public exploit or detection template: none known
- Published: 2026-10-14 · updated 2026-10-16
- Weakness: CWE-121
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).
Affected products
- NLnet Labs NSD: from 4.10.0 before 4.15.3 — fixed in 4.15.3
How to fix
Upgrade to a fixed version: NLnet Labs NSD 4.15.3. Check the vendor advisory for mitigations.
References
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