CVE-2026-7426 Out-of-Bounds Write via Unsanitized Prefix Length in Router Advertisement Processing in FreeRTOS-Plus-TCP

Medium 6.1 Published 29 Apr 2026 Updated 29 Apr 2026

An adjacent attacker can cause heap buffer overflow and potential code execution by sending crafted IPv6 Router Advertisements to devices using FreeRTOS-Plus-TCP.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Local or same network only
Victim action needed: Not needed
Fix: None listed

What is CVE-2026-7426?

CVE-2026-7426 is a medium-severity memory corruption vulnerability in AWS FreeRTOS-Plus-TCP, published on 29 Apr 2026. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

Insufficient validation of the prefix length field in IPv6 Router Advertisement processing in FreeRTOS-Plus-TCP before V4.2.6 and V4.4.1 allows an adjacent network actor to cause memory corruption by sending a crafted Router Advertisement with a prefix length value exceeding the maximum valid length, resulting in a heap buffer overflow. Users processing IPv4 RA only are not impacted.

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

Weakness: CWE-787

Which versions are affected by CVE-2026-7426?

It affects 1 product.

Products include Amazon Freertos-Plus-Tcp.

How do I fix CVE-2026-7426?

No fix has been published for CVE-2026-7426 yet. Limit exposure of the affected software until one is available.

Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.

Is CVE-2026-7426 being exploited?

There is no known exploitation of CVE-2026-7426 in the wild and no public exploit code.

Sources

Also known as GHSA-97qg-4359-xm3x.