CVE-2026-13735Network attack vector

VPN status spoofing via unauthenticated keepalives

Published Aug 28, 2026 · Updated Aug 28, 2026

Authentication bypass in Zephyr RTOS 4.4.0 through 4.4.1 allows remote attackers to spoof a VPN-connected status via forged keepalives. wg_process_data_message() returned on 16-byte transport payloads before wg_decrypt_packet() verified the Poly1305 tag, yet still emitted NET_EVENT_VPN_CONNECTED. Exploitation requires a receiving-valid session index; the flaw alters only the management status signal and does not inject traffic, disclose keys, or interrupt service.

CVSS severity3.7
Low
EPSS probability0.25%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in Zephyr RTOS 4.4.0 through 4.4.1 allows remote attackers to spoof a VPN-connected status via forged keepalives. wg_process_data_message() returned on 16-byte transport payloads before wg_decrypt_packet() verified the Poly1305 tag, yet still emitted NET_EVENT_VPN_CONNECTED. Exploitation requires a receiving-valid session index; the flaw alters only the management status signal and does not inject traffic, disclose keys, or interrupt service.

The record

CVE
CVE-2026-13735
Published
Aug 28, 2026
Updated
Aug 28, 2026
Vendor
Zephyr Project
Product
Zephyr RTOS
Classifications
CWE-290, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 28, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 28, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=4.4.0 <4.4.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Zephyr Project · Zephyr RTOSversion=4.4.0 <4.4.2

Published CVSS scores

3.7Zephyr ProjectCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-290Authentication Bypass by Spoofing
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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