---
id: CVE-2026-16512
title: >-
  gptp_handle_msg() in subsys/net/l2/ethernet/gptp/gptp.c dereferenced the gPTP
  header returned by GPTP_HDR() and switched on hdr->message_type without first
  checking that the received frame carries at least sizeof(struct gptp_hdr) (34)
  by…
summary: >-
  gptp_handle_msg() in subsys/net/l2/ethernet/gptp/gptp.c dereferenced the gPTP
  header returned by GPTP_HDR() and switched on hdr->message_type without first
  checking that the received frame carries at least sizeof(struct gptp_hdr) (34)
  by…
severity: low
cvss: 3.1
cvssVector: 'CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N'
cwe:
  - CWE-125
vendor: zephyrproject
product: zephyr
affected:
  - zephyr >= 1.13.0 < 4.4.2
published: '2026-09-18'
updated: '2026-09-18'
sourceUpdated: '2026-09-18T19:11:57.760'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-16512'
references:
  - url: >-
      https://github.com/zephyrproject-rtos/zephyr/commit/84eaf32c9301e911ad038a057f447a7836a2a2f8
    label: vulnerabilities@zephyrproject.org
  - url: >-
      https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-89r6-q468-45xq
    label: vulnerabilities@zephyrproject.org
tags:
  - nvd
  - cve.org
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-09-18T16:43:14.228181Z'
ingestedAt: '2026-09-18T14:43:13.065Z'
epss: 0.00172
epssPercentile: 0.05819
---

## Overview

gptp_handle_msg() in subsys/net/l2/ethernet/gptp/gptp.c dereferenced the gPTP header returned by GPTP_HDR() and switched on hdr->message_type without first checking that the received frame carries at least sizeof(struct gptp_hdr) (34) bytes of payload. The header accessor gptp_get_hdr() deliberately never fails for a short buffer — it returns pkt->frags->data and leaves validation to its callers — so a truncated frame produced a header pointer covering memory beyond the received data. The per-message-type checks that follow do not compensate: GPTP_VALID_LEN() reduces to len > 60 once the Ethernet header has been pulled, which is false for every fixed-size gPTP message, so GPTP_CHECK_LEN() never rejects a truncated SYNC, FOLLOWUP, PDELAY_RESP or SIGNALING message.

The defect is reached by an unauthenticated peer on the same link sending an Ethernet frame with ethertype 0x88F7 to the PTP multicast address on an interface configured as a gPTP port, with CONFIG_NET_GPTP enabled. Because conformant Ethernet pads frames to 60 bytes, a payload shorter than 34 bytes generally requires a link that can deliver sub-minimum frames — for example the native_sim TAP driver (drivers/ethernet/eth_native_tap.c), which forwards whatever length the host device supplies, or a MAC configured to accept undersized frames.

The short packet is retained (net_pkt_ref() into rcvd_sync_ptr, rcvd_follow_up_ptr, rcvd_pdelay_resp_ptr or rcvd_announce_ptr) and later parsed by the media-dependent and media-independent state machines in subsys/net/l2/ethernet/gptp/gptp_md.c and subsys/net/l2/ethernet/gptp/gptp_mi.c, which read tens of further bytes and copy some of them (the announce priority vector, hdr->port_id) into state that is subsequently transmitted. Under the default fixed-size buffer allocator (CONFIG_NET_BUF_FIXED_DATA_SIZE, 128-byte fragments) the accesses stay inside the allocated fragment and disclose stale recycled buffer contents; under the experimental CONFIG_NET_BUF_VARIABLE_DATA_SIZE allocator, where fragments are heap-allocated at the exact frame length, they are genuine out-of-bounds reads. There is no write and no availability impact.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.