{"api_version":"1","generated_at":"2026-10-21T09:31:52+00:00","cve":"CVE-2026-98809","urls":{"html":"https://cve.report/CVE-2026-98809","api":"https://cve.report/api/cve/CVE-2026-98809.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-98809","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-98809"},"summary":{"title":"Bluetooth: hci_sync: don't drain cmd_sync backlog on unregister","description":"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.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-10-18 16:17:34","updated_at":"2026-10-19 10:19:44"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/143bde97c4101ae68eb656c87e620c45b07a3090","name":"https://git.kernel.org/stable/c/143bde97c4101ae68eb656c87e620c45b07a3090","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/b1f24c1ab52345e810c42a1a81286cb5a7c92252","name":"https://git.kernel.org/stable/c/b1f24c1ab52345e810c42a1a81286cb5a7c92252","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/7f16443a30f4e86d84ae4faf057d333b41ddb757","name":"https://git.kernel.org/stable/c/7f16443a30f4e86d84ae4faf057d333b41ddb757","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/e8ba8c9c74d1035042cdf6cb5adf8f59b9b1271c","name":"https://git.kernel.org/stable/c/e8ba8c9c74d1035042cdf6cb5adf8f59b9b1271c","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-98809","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-98809","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 008ee9eb8a11bcabf12c91771dd4f470b082bd44 143bde97c4101ae68eb656c87e620c45b07a3090 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 008ee9eb8a11bcabf12c91771dd4f470b082bd44 7f16443a30f4e86d84ae4faf057d333b41ddb757 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 008ee9eb8a11bcabf12c91771dd4f470b082bd44 e8ba8c9c74d1035042cdf6cb5adf8f59b9b1271c git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 008ee9eb8a11bcabf12c91771dd4f470b082bd44 b1f24c1ab52345e810c42a1a81286cb5a7c92252 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 5.17","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.17 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.113 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.56 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.10 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["net/bluetooth/hci_sync.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"143bde97c4101ae68eb656c87e620c45b07a3090","status":"affected","version":"008ee9eb8a11bcabf12c91771dd4f470b082bd44","versionType":"git"},{"lessThan":"7f16443a30f4e86d84ae4faf057d333b41ddb757","status":"affected","version":"008ee9eb8a11bcabf12c91771dd4f470b082bd44","versionType":"git"},{"lessThan":"e8ba8c9c74d1035042cdf6cb5adf8f59b9b1271c","status":"affected","version":"008ee9eb8a11bcabf12c91771dd4f470b082bd44","versionType":"git"},{"lessThan":"b1f24c1ab52345e810c42a1a81286cb5a7c92252","status":"affected","version":"008ee9eb8a11bcabf12c91771dd4f470b082bd44","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["net/bluetooth/hci_sync.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"5.17"},{"lessThan":"5.17","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.113","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.56","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.10","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.3","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.113","versionStartIncluding":"5.17","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.56","versionStartIncluding":"5.17","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.10","versionStartIncluding":"5.17","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3","versionStartIncluding":"5.17","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"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."}],"providerMetadata":{"dateUpdated":"2026-10-19T09:26:02.636Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/143bde97c4101ae68eb656c87e620c45b07a3090"},{"url":"https://git.kernel.org/stable/c/7f16443a30f4e86d84ae4faf057d333b41ddb757"},{"url":"https://git.kernel.org/stable/c/e8ba8c9c74d1035042cdf6cb5adf8f59b9b1271c"},{"url":"https://git.kernel.org/stable/c/b1f24c1ab52345e810c42a1a81286cb5a7c92252"}],"title":"Bluetooth: hci_sync: don't drain cmd_sync backlog on unregister","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-98809","datePublished":"2026-10-18T15:48:55.913Z","dateReserved":"2026-09-25T10:25:14.371Z","dateUpdated":"2026-10-19T09:26:02.636Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-10-18 16:17:34","lastModifiedDate":"2026-10-19 10:19:44","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"98809","Ordinal":"1","Title":"Bluetooth: hci_sync: don't drain cmd_sync backlog on unregister","CVE":"CVE-2026-98809","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"98809","Ordinal":"1","NoteData":"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.","Type":"Description","Title":"Bluetooth: hci_sync: don't drain cmd_sync backlog on unregister"}]}}}