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.
CVSS breakdown
CVSS 4.0
Attack Vector
Adjacent
Attack Complexity
Low
Attack Requirements
None
Privileges Required
None
User Interaction
None
Confidentiality (Vulnerable System)
None
Integrity (Vulnerable System)
High
Availability (Vulnerable System)
None
Confidentiality (Subsequent System)
None
Integrity (Subsequent System)
None
Availability (Subsequent System)
None
CVSS 3.1
Attack Vector
Adjacent
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None
Affected products
- AWS / FreeRTOS-Plus-TCP4.0.0 – 4.2.6
- AWS / FreeRTOS-Plus-TCP4.3.0 – 4.4.1
- AWS / FreeRTOS-Plus-TCP4.2.6 – 4.2.6
- AWS / FreeRTOS-Plus-TCP4.4.1 – 4.4.1
References
- PATCHhttps://github.com/FreeRTOS/FreeRTOS-Plus-TCP/releases/tag/V4.4.1
- PATCHhttps://github.com/FreeRTOS/FreeRTOS-Plus-TCP/releases/tag/V4.2.6
- MISChttps://aws.amazon.com/security/security-bulletins/2026-021-aws/
- VENDOR_ADVISORYhttps://github.com/FreeRTOS/FreeRTOS-Plus-TCP/security/advisories/GHSA-jpw4-6h59-62w9