CVE-2026-7422

Packet-validation bypass via spoofed local MAC address

Published Apr 29, 2026 · Updated Apr 29, 2026

Packet-validation bypass in Amazon Web Services FreeRTOS-Plus-TCP before 4.2.6 and 4.4.1 allows attackers to inject malformed traffic. Its IPv4 and IPv6 receive-path loopback check treats frames whose source MAC matches a registered local endpoint as loopback traffic and skips checksum and minimum-size validation. Attackers on the adjacent network need no credentials or user interaction and can submit malformed packets that the stack processes as trusted.

CVSS severity7.1
High
EPSS probability0.18%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Packet-validation bypass in Amazon Web Services FreeRTOS-Plus-TCP before 4.2.6 and 4.4.1 allows attackers to inject malformed traffic. Its IPv4 and IPv6 receive-path loopback check treats frames whose source MAC matches a registered local endpoint as loopback traffic and skips checksum and minimum-size validation. Attackers on the adjacent network need no credentials or user interaction and can submit malformed packets that the stack processes as trusted.

The record

CVE
CVE-2026-7422
Published
Apr 29, 2026
Updated
Apr 29, 2026
Vendor
Amazon Web Services
Product
FreeRTOS-Plus-TCP
Classifications
CWE-290, CAPEC-21, T1036
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 29, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 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=4.0.0 <4.2.6
  2. Affected versionversion=4.3.0 <4.4.1

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

Amazon Web Services · FreeRTOS-Plus-TCPversion=4.0.0 <4.2.6; version=4.3.0 <4.4.1

Published CVSS scores

7.1Amazon Web ServicesCVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
6.5Amazon Web ServicesCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:H/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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-290Authentication Bypass by Spoofing
CAPEC-21Exploitation of Trusted Identifiers
T1036Masquerading

Public exploit references

No public exploit references are available in this record.

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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