CVE-2026-101338

What it is

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).

At a glance

Exploitability

Can be exploited over the network with a low-privilege account. High risk of data exposure, data tampering, service disruption.

Exploit odds

0.3% chance of exploitation in the next 30 days (EPSS).

Fix

No patch or advisory is linked yet. Look at mitigations or restrict exposure.

Timeline

1. 2026-09-28 14:39 UTC ReservedThe CVE id was reserved by its CNA
2. 2026-10-14 11:16 UTC PublishedDisclosed publicly on CVE.org and NVD
3. 2026-10-16 19:55 UTC Last updatedMost recent change to the record

Details

Published

2026-10-14 11:16 UTC

Last modified

2026-10-16 19:55 UTC

Exploit probability

0.3% · EPSS, next 30 days

Weakness

CWE-121

Record status

Awaiting Analysis

Attack profile CVSS 4.0 · 8.7

Attack vector

Network

Complexity

Low

Attack requirements

None

Privileges needed

Low

User interaction

None

Confidentiality

High

Integrity

High

Availability

High