🔍 CVE-2026-90087

0.0
CVSS Score
UNKNOWN
2026-09-17
2026-10-21 13:20
✅ 완료

🇰🇷 한글 설명

Linux 커널의 Bluetooth 스택에서 두 번째 LE 연결이 거부될 때 hci_conn 객체가 해제되지 않고 메모리에 남는 취약점입니다. 이로 인해 BT_CONNECT 상태에 잘못된 연결 정보가 영구적으로 남아 이후의 모든 LE 연결 시도가 실패하게 됩니다.

💡 쉬운 설명

블루투스 연결을 시도하다가 오류가 발생했을 때, 시스템이 사용하던 연결 정보를 제대로 지우지 못하는 문제입니다. 이 문제가 발생하면 블루투스 어댑터를 초기화하기 전까지 새로운 기기에 연결할 수 없게 됩니다.

🇺🇸 원문 (English)

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: do not leak an hci_conn when a second LE connect is rejected create_le_conn_complete() decides whether the failed connection is still pending by comparing it against hci_lookup_le_connect(), which returns the first LE connection in BT_CONNECT. That is the same connection only while at most one is pending. Two can be pending. Connections created on the passive scan path sit in BT_CONNECT with HCI_CONN_SCANNING set and are invisible to hci_lookup_le_connect() until hci_le_create_conn_sync() clears the flag when their command is issued, so the -EBUSY guard in hci_connect_le() does not prevent a second connection from being queued while the first is still on the scan path. Whenever two connections are in BT_CONNECT at once, the lookup may return one connection while create_le_conn_complete() is reporting the failure of the other; the early exit then drops the error and hci_conn_failed() never runs on the connection that failed. The controller also rejects a second HCI_OP_LE_CREATE_CONN issued while another connection creation is still outstanding, per Core Spec Vol 4, Part E. The spec calls for Command Disallowed there; the bcm43438 observed here answers with an LMP/LL error code instead, which bt_to_errno() maps to the -EPROTO (-71) in the log below. The leaked connection stays in BT_CONNECT forever, and because hci_connect_le() refuses to dial while hci_lookup_le_connect() finds anything, every subsequent attempt to reach any peer fails with -EBUSY and no command reaches the controller at all. Seen on a bcm43438 with two BLE peers polled on the same interval (state 5 is BT_CONNECT; both handles are UNSET ones, allocated from the ida above HCI_CONN_HANDLE_MAX): Bluetooth: hci1: Opcode 0x2013 failed: -71 # hcitool con < LE 14:9C:EF:03:68:81 handle 3840 state 5 lm CENTRAL < LE C4:D3:6A:8C:B5:38 handle 3841 state 5 lm CENTRAL A btmon capture across the next ten minutes of connect attempts contains no HCI_OP_LE_CREATE_CONN at all; outgoing LE connections do not recover until the adapter is reset. With this change the same scenario fails the rejected connection cleanly and further connects to both peers go through. Ask about the connection itself instead of about the device.

📍 영향받는 시스템

Linux Kernel (Bluetooth subsystem)

⚔️ 공격 벡터

특정 블루투스 컨트롤러(예: bcm43438)를 대상으로 동시에 여러 LE 연결을 시도하여 연결 상태를 고립시킴

🛡️ 대응 방법

Linux 커널을 최신 보안 패치가 적용된 버전으로 업데이트하십시오.

🔧 검증 코드

출력된 커널 버전이 해당 취약점이 수정된 패치 버전 이후인지 확인하십시오.

Shell / Script
uname -r

💻 영향받는 소프트웨어

Linux Kernel