# CVE-2026-7423: Integer Underflow in ICMP Echo Reply Processing in FreeRTOS-Plus-TCP

> CVE-2026-7423: Integer Underflow in ICMP Echo Reply Processing in FreeRTOS-Plus-TCP. CVSS 5.3 (CVSS 3.1).

Canonical: https://rewindex.com/cve/CVE-2026-7423
Last updated: 2026-06-17T11:02:24Z

- Published: 2026-04-29 18:36 UTC · Updated: 2026-06-17 11:02 UTC · Assigner: AMZN
- CVSS: 5.3 (CVSS 3.1) · Severity: Medium · Vector: CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
- EPSS: 0.22%, 13th percentile (scored 2026-10-25)
- CISA KEV: no
- CWE: CWE-191

## 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.

## Affected vendors and products

- AWS: FreeRTOS-Plus-TCP

## Tracked companies

- [Amazon Web Services](https://rewindex.com/company/aws.md)

## References

- [CVE record on cve.org](https://www.cve.org/CVERecord?id=CVE-2026-7423)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2026-7423)
- [https://aws.amazon.com/security/security-bulletins/2026-021-aws/](https://aws.amazon.com/security/security-bulletins/2026-021-aws/)
- [https://github.com/FreeRTOS/FreeRTOS-Plus-TCP/releases/tag/V4.2.6](https://github.com/FreeRTOS/FreeRTOS-Plus-TCP/releases/tag/V4.2.6)
- [https://github.com/FreeRTOS/FreeRTOS-Plus-TCP/releases/tag/V4.4.1](https://github.com/FreeRTOS/FreeRTOS-Plus-TCP/releases/tag/V4.4.1)
- [https://github.com/FreeRTOS/FreeRTOS-Plus-TCP/security/advisories/GHSA-7r59-2pgv-9v2r](https://github.com/FreeRTOS/FreeRTOS-Plus-TCP/security/advisories/GHSA-7r59-2pgv-9v2r)

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_Sources: CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (https://www.cve.org/) This product uses data from the NVD API but is not endorsed or certified by the NVD. (https://nvd.nist.gov/) Known Exploited Vulnerabilities catalog from CISA. (https://www.cisa.gov/known-exploited-vulnerabilities-catalog) EPSS scores from FIRST (Exploit Prediction Scoring System). (https://www.first.org/epss/)_


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Canonical: https://rewindex.com/cve/CVE-2026-7423 · Markdown: https://rewindex.com/cve/CVE-2026-7423.md · JSON: https://rewindex.com/api/v1/cves/CVE-2026-7423 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-10-26T03:10:15.485Z