---
id: "CVE-2026-102486"
kind: "vulnerability"
aliases: ["CVE-2026-102486"]
title: "NTPsec ntpd: oversized NTS nonce field lets remote attackers crash the daemon"
severity: "high"
cvss: 7.5
epss: 0.0075
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["infrastructure", "linux", "ntp", "ntpsec", "runtime", "self-hosted"]
not_affected_if: ["other-ntp-implementation", "version-outside-range"]
published_at: "2026-10-21T16:17:14+00:00"
first_seen_at: "2026-10-23T21:57:29+00:00"
updated_at: "2026-10-25T03:16:46+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-102486", "first_seen_at": "2026-10-23T21:57:29+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-102486", "first_seen_at": "2026-10-24T13:15:54+00:00"}]
---

# NTPsec ntpd: oversized NTS nonce field lets remote attackers crash the daemon

NTPsec ntpd versions 1.1.4 through 1.2.5 read past the end of a buffer when parsing NTS Authenticator and Encrypted Extension Fields. A remote attacker can send a packet with an oversized nonce length to crash the daemon.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Run `ntpd --version` or `ntpq -c version` on each host running NTPsec and compare against the affected range 1.1.4 through 1.2.5.
- Check whether NTS is enabled in the NTP configuration (`nts` directives in `ntp.conf`); the sources do not say whether the flaw requires NTS to be configured.

## Fix

- Upgrade NTPsec to a release later than `1.2.5`; the sources do not name the fixed version.
- Until patched, restrict which networks can reach the NTP service port (UDP `123`) where possible.

## Timeline

- 2026-10-23T21:57:29+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-102486
- 2026-10-24T13:15:54+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2026-102486

## From the sources

Out-of-bounds read in NTS extension field parsing in NTPsec ntpd 1.1.4 through 1.2.5 allows a remote attacker to crash the daemon via an NTS Authenticator and Encrypted Extension Fields (AEEF) field with an oversized nonce length.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_