Live › vulnerability › GHSA-h4fw-pv82-p7h5
Go to dashboardFreeRTOS-Plus-TCP accepts IPv6 Router Advertisements from off-link sources and accepts DNS replies without checking they came from the queried server. A remote attacker can change an embedded device's IPv6 gateway and prefix, or insert a chosen address into its DNS cache, to intercept or redirect its traffic.
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.
Embedded and IoT devices built on FreeRTOS-Plus-TCP at version V4.4.1 or earlier. The Router Advertisement issue is reachable in the default configuration where IPv6 and RA are enabled, while the DNS issue applies to any device that resolves names with the library's resolver. Devices that do not use this library, or run a newer version with the DNS check enabled, can skip it.
No product ranges from the sources yet.
V4.4.2 or later to be fixed.FreeRTOSIPConfig.h for ipconfigUSE_IPv6 and ipconfigUSE_RA set to ipconfigENABLE, and for ipconfigDNS_CHECK_REPLY_SOURCE_IP being set.V4.4.2 and patch any forked or derivative copies.ipconfigDNS_CHECK_REPLY_SOURCE_IP in FreeRTOSIPConfig.h, since upgrading alone does not fix it.ipconfigUSE_RA to ipconfigDISABLE where IPv6 RA autoconfiguration is not needed; there is no configuration-only workaround for the DNS issue.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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