CVE-2026-7423

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.

CVSS v3.1 Score

5.3

MEDIUM

CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS — Exploit Prediction

0.0002

Probability of exploitation

0.07%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-191 CWE-191

Affected Products

Vendor	Product	Versions
amazon	freertos-plus-tcp	4.0.0 — 4.2.6
amazon	freertos-plus-tcp	4.3.0 — 4.4.1

References

Advisories & Patches

https://aws.amazon.com/security/security-bulletins/2026-021-aws/ https://github.com/FreeRTOS/FreeRTOS-Plus-TCP/security/advisories/GHSA-7r59-2pgv-9v2r

Other References

https://github.com/FreeRTOS/FreeRTOS-Plus-TCP/releases/tag/V4.2.6 https://github.com/FreeRTOS/FreeRTOS-Plus-TCP/releases/tag/V4.4.1

Frequently Asked Questions

What is CVE-2026-7423? +

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. It has a CVSS v3.1 base score of 5.3 (MEDIUM).

How severe is CVE-2026-7423? +

CVE-2026-7423 has a CVSS v3.1 score of 5.3 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0002, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-7423? +

CVE-2026-7423 affects products from amazon, specifically: freertos-plus-tcp. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-7423? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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