CVE-2026-102551 & CVE-2026-102552 - Issue with FreeRTOS-Plus-TCP

Bulletin ID: 2026-139-AWS

Scope: AWS

Content Type: Important (requires attention)

Publication Date: 10/16/2026 10:15 AM PDT

Description:

FreeRTOS-Plus-TCP is an open-source, thread-safe TCP/IP stack for the FreeRTOS kernel, distributed by Amazon for use on embedded and IoT devices. AWS identified two issues with FreeRTOS-Plus-TCP, affecting multiple versions.

CVE-2026-102551: improper verification of the source of a communication channel in the IPv6 Router Advertisement handler. The handler does not fully validate that a received Router Advertisement originates from an on-link source before acting on it. Under certain conditions, a remote third-party might influence an endpoint's IPv6 gateway, prefix, and address configuration, potentially enabling interception of the device's IPv6 traffic.

This issue is reachable in the library's default configuration, where ipconfigUSE_IPv6 and ipconfigUSE_RA are both enabled.

CVE-2026-102552: improper verification of the source of a communication channel in the DNS resolver. The resolver does not fully validate that a DNS reply originates from the server that was queried before accepting it. Under certain conditions, a remote third-party might insert a chosen address into the device's DNS cache, potentially redirecting the device's subsequent connections for the affected name.

Impacted versions:

- CVE-2026-102551 (Router Advertisement): <= V4.4.1

- CVE-2026-102552 (DNS resolver): <= V4.4.1

Please refer to the article below for the most up-to-date and complete information related to this AWS Security Bulletin.