---
id: "CVE-2026-102485"
kind: "vulnerability"
aliases: ["CVE-2026-102485"]
title: "NTPsec: out-of-bounds read in Oncore GPS driver crashes ntpd or leaks memory"
severity: "medium"
cvss: 5.2
epss: 0.00238
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["ntp", "ntpsec", "package", "self-hosted", "time-servers"]
not_affected_if: ["no-oncore-refclock", "ntpd-1.2.6-or-later"]
published_at: "2026-10-21T16:17:14+00:00"
first_seen_at: "2026-10-23T21:57:29+00:00"
updated_at: "2026-10-25T04:28:47+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-102485", "first_seen_at": "2026-10-23T21:57:29+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-102485", "first_seen_at": "2026-10-24T13:15:54+00:00"}]
---

# NTPsec: out-of-bounds read in Oncore GPS driver crashes ntpd or leaks memory

The Motorola Oncore reference clock driver in NTPsec ntpd reads past a buffer when a PPS Control reply carries an out-of-range mode byte. An attacker who controls the GPS receiver's serial data can crash ntpd or read process memory.

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

## How to check

- Run `ntpd --version` or `ntpq -c version` and compare against `1.2.6`
- Check whether the Oncore refclock driver is configured, e.g. `grep -i oncore /etc/ntp.conf` or `grep -i oncore /etc/ntpsec/ntp.conf`

## Fix

- Upgrade NTPsec to `1.2.6` or later
- Until patched, remove or disable Oncore refclock lines in the ntp configuration

## Timeline

- 2026-10-23T21:57:29+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-102485
- 2026-10-24T13:15:54+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2026-102485

## From the sources

Out-of-bounds read in the Motorola Oncore refclock driver in NTPsec ntpd before 1.2.6 allows an attacker who controls the GPS receiver's serial data to crash ntpd or disclose memory via a PPS Control (@@Gc) reply with an out-of-range mode byte.

---

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