CVE-2026-7656Public exploit

Traffic hijacking via bypassed IPv6 ND validation

Published Jun 29, 2026 · Updated Jun 29, 2026

IPv6 Neighbor Discovery validation in Zephyr RTOS 1.14.0 through 4.4.0 allows remote attackers to inject forged RA, NS, and NA packets. The handle_ra_input, handle_ns_input, and handle_na_input predicates join required length, hop-limit, address, and target checks to the ICMPv6 code test with &&, so normal code 0 makes the entire drop condition false. IPv6 must be enabled and packet injection must be possible; accepted messages can redirect traffic, poison neighbor caches, alter network parameters, or interrupt service.

CVSS severity8.1
High
EPSS probability0.33%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

IPv6 Neighbor Discovery validation in Zephyr RTOS 1.14.0 through 4.4.0 allows remote attackers to inject forged RA, NS, and NA packets. The handle_ra_input, handle_ns_input, and handle_na_input predicates join required length, hop-limit, address, and target checks to the ICMPv6 code test with &&, so normal code 0 makes the entire drop condition false. IPv6 must be enabled and packet injection must be possible; accepted messages can redirect traffic, poison neighbor caches, alter network parameters, or interrupt service.

The record

CVE
CVE-2026-7656
Published
Jun 29, 2026
Updated
Jun 29, 2026
Vendor
Zephyr Project
Product
Zephyr RTOS
Classifications
CWE-670, CWE-290, T1557
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 29, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 29, 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=1.14.0 <4.5.0

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

Zephyr Project · Zephyr RTOSversion=1.14.0 <4.5.0

Published CVSS scores

8.1Zephyr ProjectCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
6.8NIST NVDCVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:H

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)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-670Always-Incorrect Control Flow Implementation
CWE-290Authentication Bypass by Spoofing
T1557Adversary-in-the-Middle

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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