CVE-2026-31622

/* * Conceptual PoC for CVE-2026-31622 * This C code simulates the vulnerable logic in the kernel where * bounds checking was missing for the NFC-A cascade depth. * * Compile: gcc -o poc_cve2026_31622 poc_cve2026_31622.c */ #include <stdio.h> #include <string.h> #include <stdlib.h> #define NFC_NFCID1_MAXSIZE 10 #define CASCADE_LEVELS 3 struct nfc_target { int nfcid1_len; unsigned char nfcid1[NFC_NFCID1_MAXSIZE]; }; // Simulates the vulnerable behavior (before patch) void vulnerable_sdd_res_handler(struct nfc_target *target, int payload_len, unsigned char *payload) { printf("[VULNERABLE] Handling SDD response...\n"); // Missing check: if (target->nfcid1_len + payload_len > NFC_NFCID1_MAXSIZE) memcpy(target->nfcid1 + target->nfcid1_len, payload, payload_len); target->nfcid1_len += payload_len; printf("Current nfcid1_len: %d\n", target->nfcid1_len); } // Simulates the patched behavior void patched_sdd_res_handler(struct nfc_target *target, int payload_len, unsigned char *payload) { printf("[PATCHED] Handling SDD response...\n"); if (target->nfcid1_len + payload_len > NFC_NFCID1_MAXSIZE) { printf("Error: UID exceeds buffer size! Rejecting response.\n"); return; } memcpy(target->nfcid1 + target->nfcid1_len, payload, payload_len); target->nfcid1_len += payload_len; printf("Current nfcid1_len: %d\n", target->nfcid1_len); } int main() { struct nfc_target target = {0}; unsigned char fake_payload[4] = {0x11, 0x22, 0x33, 0x44}; int payload_size = 4; printf("--- Simulating Attack (Sending 4 levels of cascade) ---\n"); // Level 1 vulnerable_sdd_res_handler(&target, payload_size, fake_payload); // Level 2 vulnerable_sdd_res_handler(&target, payload_size, fake_payload); // Level 3 (Normally max) vulnerable_sdd_res_handler(&target, payload_size, fake_payload); // Level 4 (Overflow trigger) vulnerable_sdd_res_handler(&target, payload_size, fake_payload); printf("\nFinal nfcid1_len: %d (Buffer size: %d)\n", target.nfcid1_len, NFC_NFCID1_MAXSIZE); if (target.nfcid1_len > NFC_NFCID1_MAXSIZE) { printf("Heap buffer overflow occurred!\n"); } return 0; }

{"cve": {"id": "CVE-2026-31622", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-04-24T15:16:41.487", "lastModified": "2026-04-28T14:14:07.097", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nNFC: digital: Bounds check NFC-A cascade depth in SDD response handler\n\nThe NFC-A anti-collision cascade in digital_in_recv_sdd_res() appends 3\nor 4 bytes to target->nfcid1 on each round, but the number of cascade\nrounds is controlled entirely by the peer device. The peer sets the\ncascade tag in the SDD_RES (deciding 3 vs 4 bytes) and the\ncascade-incomplete bit in the SEL_RES (deciding whether another round\nfollows).\n\nISO 14443-3 limits NFC-A to three cascade levels and target->nfcid1 is\nsized accordingly (NFC_NFCID1_MAXSIZE = 10), but nothing in the driver\nactually enforces this. This means a malicious peer can keep the\ncascade running, writing past the heap-allocated nfc_target with each\nround.\n\nFix this by rejecting the response when the accumulated UID would exceed\nthe buffer.\n\nCommit e329e71013c9 (\"NFC: nci: Bounds check struct nfc_target arrays\")\nfixed similar missing checks against the same field on the NCI path."}], "metrics": {"cvssMetricV31": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 8.8, "baseSeverity": "HIGH", "attackVector": "ADJACENT_NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 2.8, "impactScore": 5.9}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-120"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.13", "versionEndExcluding": "6.6.136", "matchCriteriaId": "6E4B7C62-D2BF-4255-BC77-4D30A01DC46D"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.7", "versionEndExcluding": "6.12.83", "matchCriteriaId": "7F0AE5B5-23AC-4DCC-B37A-51CA1DAE7BA8"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13", "versionEndExcluding": "6.18.24", "matchCriteriaId": "8126B8B8-6D0B-4443-86C1-672AEE893555"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19", "versionEndExcluding": "6.19.14", "matchCriteriaId": "D6A8A074-BBF4-4803-ABED-519A839435BB"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "7.0", "versionEndExcluding": "7.0.1", "matchCriteriaId": "9B5888AB-7403-4335-89E4-21CC0B48366A"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/1bec5698b55aa2be5c3b983dba657c01d0fd3dbc", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/2819f34e08bdffb6f06a51c67948ec5737fb166a", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/46ce8be2ced389bccd84bcc04a12cf2f4d0c22d1", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/5a59bf70c38ee1eb4be03bab830bbc3a6f0bd1f1", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/8d9d9bf3565271ca7ab9c716a94e87296177e7ba", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/cc024a3de265ef6c58957f4990eccb9f806208cb", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}]}}