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CVE-2026-98809— Bluetooth: hci_sync: don't drain cmd_sync backlog on unregister

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

在 Linux 内核中，以下漏洞已得到修复： 蓝牙：hci_sync 模块——在注销设备时不再清空 cmd_sync 积压队列 函数会先禁用 和 ，随后调用 。该函数中的 会等待 返回。而该工作线程会逐个出队并执行 中的所有条目。由于此时 已被禁用，任何队列中的 HCI 命令都无法被发送到控制器，因此每个已排队的 HCI 命令都会等待完整的 （2 秒）。 该积压队列没有上限。用户空间可以持续向一个无响应的控制器排队 MGMT 命令（例如 ）。当关闭 时， 会因等待积压队列处理而阻塞，耗时约为“积压条目数 × 2 秒

AI Predicted 4.9 Difficulty: Moderate

Affected Version Matrix 10

VendorProduct Version RangeStatus
Linux Linux 008ee9eb8a11bcabf12c91771dd4f470b082bd44< 143bde97c4101ae68eb656c87e620c45b07a3090 affected
008ee9eb8a11bcabf12c91771dd4f470b082bd44< 7f16443a30f4e86d84ae4faf057d333b41ddb757 affected
008ee9eb8a11bcabf12c91771dd4f470b082bd44< e8ba8c9c74d1035042cdf6cb5adf8f59b9b1271c affected
008ee9eb8a11bcabf12c91771dd4f470b082bd44< b1f24c1ab52345e810c42a1a81286cb5a7c92252 affected
5.17 affected
< 5.17 unaffected
6.12.113≤ 6.12.* unaffected
6.18.56≤ 6.18.* unaffected
… +2 more rows
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I. Basic Information for CVE-2026-98809

Vulnerability Information
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Vulnerability Title
Bluetooth: hci_sync: don't drain cmd_sync backlog on unregister
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: Bluetooth: hci_sync: don't drain cmd_sync backlog on unregister hci_unregister_dev() disables cmd_work and cmd_timer, then calls hci_cmd_sync_clear(), whose cancel_work_sync() waits for hci_cmd_sync_work() to return. That worker dequeues and runs every entry on cmd_sync_work_list. With cmd_work disabled nothing reaches the controller, so each queued HCI command waits the full HCI_CMD_TIMEOUT (2s). The backlog has no bound. Userspace can keep queuing MGMT commands such as MGMT_OP_GET_CLOCK_INFO against a controller that doesn't answer. Closing /dev/vhci then blocks in vhci_release() for backlog * 2s: INFO: task syz-executor:5749 blocked for more than 143 seconds. cancel_work_sync hci_cmd_sync_clear hci_unregister_dev vhci_release In a local reproduction the backlog held more than 5000 entries, which comes to hours of hang. Stop the worker from taking new entries once HCI_UNREGISTER is set, and wake any request still waiting with -ENODEV before cancelling the work. The entries left over are destroyed with -ECANCELED by the existing sweep in hci_cmd_sync_clear(). They stay on the list until the work has stopped, so hci_cmd_sync_dequeue() and friends still see them. A callback already running may still issue another command, which delays unregister by at most one timeout per remaining command, not by the whole backlog.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 008ee9eb8a11bcabf12c91771dd4f470b082bd44 ~ 143bde97c4101ae68eb656c87e620c45b07a3090 -
Linux Linux 5.17 -

II. Public POCs for CVE-2026-98809

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III. Intelligence Information for CVE-2026-98809

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Patches & Fixes for CVE-2026-98809 (4)

Same Patch Batch · Linux · 2026-10-18 · 436 CVEs total

CVE-2026-98582 nfc: st21nfca: validate received frame size
CVE-2026-98568 vxlan: use one headroom snapshot for neighbour replies
CVE-2026-98570 net: ipv6: keep room for the mac header in dst_dev_overhead()
CVE-2026-98571 net: stmmac: clear stale buf->page after recycling on skb build failure
CVE-2026-98572 bpf: Fix immediate JMP JEQ/JNE on MIPS32
CVE-2026-98573 net: skbuff: fix pull-bound underflow in skb_checksum_setup_ipv6()
CVE-2026-98574 net: bcmgenet: stop Tx NAPI before disabling the queues
CVE-2026-98575 nfc: pn533: fix OOB read in pn533_acr122_is_rx_frame_valid()
CVE-2026-98576 nfc: llcp: fix slab-out-of-bounds reads when logging service names
CVE-2026-98577 nfc: llcp: fix WKS SAP hijacking via prefix match in nfc_llcp_wks_sap()
CVE-2026-98578 nfc: st21nfca: validate ISO15693 inventory length
CVE-2026-98579 nfc: llcp: fix sdreq TLV list leak on parse/alloc/send failure
CVE-2026-98580 nfc: llcp: Fix race condition in accept_queue lifecycle
CVE-2026-98581 nfc: llcp: Fix list corruption / refcount desync in nfc_llcp_recv_dm()
CVE-2026-98593 s390/debug: Fix NULL pointer dereference in debug_info_copy()
CVE-2026-98590 bpf: Fix bpf_sock context code generation
CVE-2026-98591 bpf: Fix bounds check for skb-backed dynptrs
CVE-2026-98592 net: spacemit: clear TX descriptor on fragment mapping failure
CVE-2026-98589 bpf: Reject pkt arguments in mutating subprogs
CVE-2026-98594 tg3: clean up PHYLIB resources on probe failure

Showing top 20 of 436 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-98809

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