Integer underflow in the ICMP and ICMPv6 echo reply handlers in FreeRTOS-Plus-TCP before V4.4.1 and V4.2.6 allows an adjacent network user to cause a denial of service (device crash) when outgoing ping support is enabled, because header sizes are subtracted from a packet length field without validating the field is large enough, resulting in a heap out-of-bounds read of up to approximately 65KB.



To mitigate this issue, users should upgrade to the fixed version when available.

Attack Vector Adjacent Network

Attack Complexity Low

Privileges Required None

Attack Requirements Present

User Interaction None

Vulnerable System Confidentiality Impact None

Vulnerable System Integrity Impact None

Vulnerable System Availability Impact High

Subsequent System Confidentiality Impact None

Subsequent System Integrity Impact None

Subsequent System Availability Impact None

Attack Vector Adjacent Network

Attack Complexity High

Privileges Required None

Scope Unchanged

Confidentiality Impact None

Integrity Impact None

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

No EPSS score available.

Exploitation none

Automatable no

Technical Impact partial

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions
AWS FreeRTOS-Plus-TCP unaffected
Version Status Constraints
4.0.0 affected < 4.2.6
4.3.0 affected < 4.4.1
4.2.6 unaffected —
4.4.1 unaffected —

No data.

No data.

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No data.

Project Subscriptions

No data.

Advisories

No advisories yet.

Fixes

Solution

No solution given by the vendor.

Workaround

No workaround given by the vendor.

References
Link Providers
https://aws.amazon.com/security/security-bulletins/2026-021-aws/ cve-icon cve-icon
https://github.com/FreeRTOS/FreeRTOS-Plus-TCP/releases/tag/V4.2.6 cve-icon cve-icon
https://github.com/FreeRTOS/FreeRTOS-Plus-TCP/releases/tag/V4.4.1 cve-icon cve-icon
https://github.com/FreeRTOS/FreeRTOS-Plus-TCP/security/advisories/GHSA-7r59-2pgv-9v2r cve-icon cve-icon
History

Wed, 29 Apr 2026 19:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Wed, 29 Apr 2026 19:00:00 +0000

Type Values Removed Values Added
Description Integer underflow in the ICMP and ICMPv6 echo reply handlers in FreeRTOS-Plus-TCP before V4.4.1 and V4.2.6 allows an adjacent network user to cause a denial of service (device crash) when outgoing ping support is enabled, because header sizes are subtracted from a packet length field without validating the field is large enough, resulting in a heap out-of-bounds read of up to approximately 65KB. To mitigate this issue, users should upgrade to the fixed version when available.
Title Integer Underflow in ICMP Echo Reply Processing in FreeRTOS-Plus-TCP
Weaknesses CWE-191
References
Metrics cvssV3_1

{'score': 5.3, 'vector': 'CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H'}

cvssV4_0

{'score': 6, 'vector': 'CVSS:4.0/AV:A/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N'}

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: AMZN

Published:

Updated: 2026-04-29T19:08:11.602Z

Reserved: 2026-04-29T14:27:49.474Z

Link: CVE-2026-7423

cve-icon Vulnrichment

Updated: 2026-04-29T19:08:07.142Z

cve-icon NVD

Status : Received

Published: 2026-04-29T19:16:26.617

Modified: 2026-04-29T19:16:26.617

Link: CVE-2026-7423

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-04-29T21:15:16Z

Weaknesses