---
title: "CVE-2026-19673: Zephyr OS - Out of Bounds Read/Write"
description: "Zephyr OS with CONFIG_NET_VLAN=y and VLAN enabled on Ethernet interfaces without hardware VLAN tag stripping contains a buffer length validation flaw in ethernet_recv() caused by improper length checks on VLAN tagged frames, letting remote attackers cause denial of service and out-of-bounds memory access, exploit requires crafted short VLAN tagged Ethernet frames."
url: https://panop.io/threat-heartbeat/CVE-2026-19673/
---

# CVE-2026-19673 Zephyr OS - Out of Bounds Read/Write

Zephyr OS with CONFIG\_NET\_VLAN=y and VLAN enabled on Ethernet interfaces without hardware VLAN tag stripping contains a buffer length validation flaw in ethernet\_recv() caused by improper length checks on VLAN tagged frames, letting remote attackers cause denial of service and out-of-bounds memory access, exploit requires crafted short VLAN tagged Ethernet frames.

CVSS base score 7.1 /10

High

CISA KEV

Not listed

Public exploit

None known

Authentication

Not required

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-19673)

## Details

Type

Out of Bounds Read/Write

Impact

Denial Of Service, Information Disclosure, Data Tampering

CVSS vector

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H

Published

14 October 2026

Updated

15 October 2026

Weakness

[CWE-125](https://cwe.mitre.org/data/definitions/125.html)

## Vendor fix

Update to a version that rejects frames with invalid VLAN tag lengths and validates header length against buffer length.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

## References

- [https://nvd.nist.gov/vuln/detail/CVE-2026-19673](https://nvd.nist.gov/vuln/detail/CVE-2026-19673)
- [https://github.com/zephyrproject-rtos/zephyr/commit/fd3c6fedf6b639977a80e52b680b15672c31f3ef](https://github.com/zephyrproject-rtos/zephyr/commit/fd3c6fedf6b639977a80e52b680b15672c31f3ef)
- [https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-79rf-rwff-f4vg](https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-79rf-rwff-f4vg)

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## What this record can't tell you

- Whether you run the affected software, and where
- Whether an attacker can actually reach and exploit it
- The misconfigurations that never get a CVE number
- What it would cost the business, ranked into what to fix first

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