{"id":"AZL-108714","summary":"CVE-2026-98809 affecting package kernel 6.6.157.1-1","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: hci_sync: don't drain cmd_sync backlog on unregister\n\nhci_unregister_dev() disables cmd_work and cmd_timer, then calls\nhci_cmd_sync_clear(), whose cancel_work_sync() waits for\nhci_cmd_sync_work() to return. That worker dequeues and runs every\nentry on cmd_sync_work_list. With cmd_work disabled nothing reaches\nthe controller, so each queued HCI command waits the full\nHCI_CMD_TIMEOUT (2s).\n\nThe backlog has no bound. Userspace can keep queuing MGMT commands\nsuch as MGMT_OP_GET_CLOCK_INFO against a controller that doesn't\nanswer. Closing /dev/vhci then blocks in vhci_release() for\nbacklog * 2s:\n\n  INFO: task syz-executor:5749 blocked for more than 143 seconds.\n   cancel_work_sync\n   hci_cmd_sync_clear\n   hci_unregister_dev\n   vhci_release\n\nIn a local reproduction the backlog held more than 5000 entries,\nwhich comes to hours of hang.\n\nStop the worker from taking new entries once HCI_UNREGISTER is set,\nand wake any request still waiting with -ENODEV before cancelling\nthe work. The entries left over are destroyed with -ECANCELED by the\nexisting sweep in hci_cmd_sync_clear(). They stay on the list until\nthe work has stopped, so hci_cmd_sync_dequeue() and friends still see\nthem. A callback already running may still issue another command,\nwhich delays unregister by at most one timeout per remaining command,\nnot by the whole backlog.","modified":"2026-10-19T14:16:49.064881101Z","published":"2026-10-18T16:17:34Z","upstream":["CVE-2026-98809"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-98809"}],"affected":[{"package":{"name":"kernel","ecosystem":"Azure Linux:3","purl":"pkg:rpm/azure-linux/kernel"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"last_affected":"6.6.157.1-1"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-108714.json"}}],"schema_version":"1.9.0"}