Live › vulnerability › GHSA-pjq5-fqrr-g6pv
Go to dashboardFreeRTOS-Plus-TCP up to V4.4.1 accepts IPv6 Router Advertisements and DNS replies without properly checking their source, so a remote third party can change a device's IPv6 gateway and prefix or insert a chosen address into its DNS cache. An attacker could use this to intercept IPv6 traffic or redirect the device's later connections to hosts they control.
Summary written from the sources below. Check the originals before acting.
First seen by InfraStack 2026-10-24 18:56 UTC. All times on this page are UTC.
Devices built on FreeRTOS-Plus-TCP up to V4.4.1 are exposed, including IoT and embedded products that use the stack and any forks or derivatives of it. The Router Advertisement issue is reachable in the default configuration with IPv6 and RA enabled, and the DNS issue applies to any device that performs DNS lookups with the stack. Teams that do not ship FreeRTOS-Plus-TCP, or that run it on versions at or above V4.4.2 with the DNS source check enabled, can skip it.
No product ranges from the sources yet.
FreeRTOS_IPv6.h and FreeRTOS_DNS.c in the imported code.FreeRTOSIPConfig.h for ipconfigUSE_IPv6 and ipconfigUSE_RA set to ipconfigENABLE, which is the default configuration that is affected.FreeRTOSIPConfig.h for ipconfigDNS_CHECK_REPLY_SOURCE_IP; if it is absent or not enabled, the DNS fix is not active.V4.4.2 or later, and patch any forked or derivative copies of the code.ipconfigDNS_CHECK_REPLY_SOURCE_IP in FreeRTOSIPConfig.h after upgrading, since the DNS fix is opt-in and disabled by default.ipconfigUSE_RA to ipconfigDISABLE (or disable IPv6 with ipconfigUSE_IPv6 = ipconfigDISABLE) where IPv6 autoconfiguration is not needed.Each row is the first time that source carried this signal. The analyst’s rows are its own findings.
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:
Resolution:
This issue has been addressed in FreeRTOS-Plus-TCP version V4.4.2. We recommend upgrading to the latest version and ensuring any forked or derivative code is patched to incorporate the new fixes.
For the DNS resolver issue, responder source-IP validation is provided as an opt-in option and is disabled by default; upgrading alone does not remediate it. To remediate, upgrade to V4.4.2 and enable ipconfigDNS_CHECK_REPLY_SOURCE_IP in FreeRTOSIPConfig.h.
Workarounds:
References:
Acknowledgement:
We would like to thank Cipher / Causal Security for collaborating on this issue through the coordinated vulnerability disclosure process.
Please email [email protected] with any security questions or concerns.
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