Description
Insufficient packet validation in FreeRTOS-Plus-TCP before V4.2.6 and V4.4.1 allows an adjacent network actor to bypass all checksum and minimum-size validation by spoofing the Ethernet source MAC address to match one of the device's own registered endpoints, because the loopback detection mechanism skips all input validation for packets whose source MAC matches a local endpoint. To mitigate this issue, users should upgrade to the fixed version when available.
Affected products
amazon: freertos-plus-tcp
References4
- aws.amazon.com/security/security-bulletins/2026-021-aws/ Vendor Advisory
- github.com/FreeRTOS/FreeRTOS-Plus-TCP/security/advisories/GHSA-… PatchVendor Advisory
- github.com/FreeRTOS/FreeRTOS-Plus-TCP/releases/tag/V4.2.6 Release Notes
- github.com/FreeRTOS/FreeRTOS-Plus-TCP/releases/tag/V4.4.1 Release Notes
Metrics
- CVSS 3.1
-
6.5
MEDIUM
Score source: CNA
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N - CVSS 4.0
-
7.1
HIGH
Score source: CNA
CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - EPSS — exploit probability
- 0% percentile: 7 · as of 13 November 2026
- CWE
- CWE-290
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