Issue with FreeRTOS-Plus-TCP - MAC Address Validation Bypass and ICMP Echo Reply Integer Underflow

Bulletin ID: 2026-021-AWS Scope: AWS Content Type: Important (requires attention) Publication Date: 2026/04/29 12:00 PM PDT Description: FreeRTOS-Plus-TCP is a scalable, open source, and thread-safe TCP/IP stack for FreeRTOS. - CVE-2026-7422: Insufficient packet validation in the IPv4 and IPv6 receive paths allows an adjacent network device to send a packet that bypasses checksum and minimum-size validation by spoofing the Ethernet source MAC address to match one of the target device's own registered endpoints. - CVE-2026-7423: Integer underflow in the ICMP and ICMPv6 echo reply handlers allows an adjacent network device 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. Impacted versions: >=V4.0.0 AND =V4.3.0 AND Please refer to the article below for the most up-to-date and complete information related to this AWS Security Bulletin.