{"id":"CVE-2026-98737","kind":"vulnerability","aliases":["CVE-2026-98737"],"related":[],"title":"Linux kernel Bluetooth: inquiry cache use-after-free can crash or corrupt memory","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: hci_sync: Fix inquiry cache use-after-free\n\nThe sync command worker holds hdev->req_lock, but inquiry-cache updates\nand flushes use hdev->lock. Both hci_acl_create_conn_sync() and\nhci_stop_discovery_sync() look up entries and read their fields without\ntaking hdev->lock.\n\nAfter either lookup returns, a concurrent HCIINQUIRY ioctl can acquire\nhdev->lock and flush the cache, freeing the entry. The worker then reads\nthe freed entry while preparing a create-connection or remote-name-cancel\ncommand. The list traversal also races with cache updates and removal.\n\nKASAN reported these accesses:\n\n  BUG: KASAN: slab-use-after-free in hci_acl_create_conn_sync+0x5f1/0x650\n  Workqueue: hci0 hci_cmd_sync_work\n  Call Trace:\n   hci_acl_create_conn_sync+0x5f1/0x650\n   hci_cmd_sync_work+0x13c/0x290\n\n  Allocated by task 90:\n   hci_inquiry_cache_update+0x3e6/0x7d0\n   hci_inquiry_result_evt+0x3cb/0x560\n\n  Freed by task 93:\n   hci_inquiry_cache_flush+0x111/0x2b0\n   hci_inquiry+0x2f2/0x780\n   hci_sock_ioctl+0x269/0x5f0\n\n  BUG: KASAN: slab-use-after-free in hci_stop_discovery_sync+0x3b1/0x3c0\n  Workqueue: hci0 hci_cmd_sync_work\n  Call Trace:\n   hci_stop_discovery_sync+0x3b1/0x3c0\n   hci_cmd_sync_work+0x173/0x300\n\n  Allocated by task 86:\n   hci_inquiry_cache_update+0x483/0x940\n   hci_inquiry_result_evt+0x3cb/0x560\n\n  Freed by task 91:\n   hci_inquiry_cache_flush+0x13e/0x2f0\n   hci_inquiry+0x2f2/0x780\n   hci_sock_ioctl+0x269/0x5f0\n\nHold hdev->lock across each lookup and all reads from its result. Copy the\nremote address before unlocking so discovery cancellation does not retain\na cache entry pointer. Release the lock before sending synchronous HCI\ncommands, since their completion handlers may need the same lock.","summary":"A race in the Linux kernel Bluetooth HCI code lets the inquiry cache be flushed while a sync worker still reads a freed entry. The sources describe a use-after-free that KASAN caught, and do not state what an attacker can achieve beyond that.","severity":"unknown","cvss":null,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["bluetooth","linux-kernel","package","self-hosted"],"not_affected_if":["bluetooth-module-not-loaded","no-bluetooth-hardware"],"how_to_check":"- `uname -r` and compare against the fixed kernel builds listed in the NVD entry\n- `lsmod | grep -i bluetooth` to see whether the Bluetooth stack is loaded at all","fix":"- Update the Linux kernel to a build that includes the upstream fix for CVE-2026-98737 (the version is unknown from the sources)\n- Until patched, unloading the Bluetooth modules (`modprobe -r bluetooth`) on hosts that do not need Bluetooth removes the exposed code path","status":"open","published_at":"2026-10-18T16:17:27+00:00","first_seen_at":"2026-10-23T21:57:16+00:00","triaged_at":"2026-10-25T05:17:09+00:00","updated_at":"2026-10-25T05:17:09+00:00","category":"package","confidence":0.4,"triage":{"at":"2026-10-25T05:17:09Z","model":"claude-haiku-5-5","output":{"fix":"- Update the Linux kernel to a build that includes the upstream fix for CVE-2026-98737 (the version is unknown from the sources)\n- Until patched, unloading the Bluetooth modules (`modprobe -r bluetooth`) on hosts that do not need Bluetooth removes the exposed code path","reach":"local","title":"Linux kernel Bluetooth: inquiry cache use-after-free can crash or corrupt memory","impact":"medium","summary":"A race in the Linux kernel Bluetooth HCI code lets the inquiry cache be flushed while a sync worker still reads a freed entry. The sources describe a use-after-free that KASAN caught, and do not state what an attacker can achieve beyond that.","category":"package","nicknames":[],"who_cares":["linux-kernel","bluetooth","self-hosted"],"confidence":0.4,"needs_auth":"unknown","worst_case":"unknown; kernel memory corruption from a use-after-free","analyst_note":"Check the NVD entry and the linked upstream kernel commit for affected version ranges, the fixed stable versions, and whether the bug is reachable without local access.","how_to_check":"- `uname -r` and compare against the fixed kernel builds listed in the NVD entry\n- `lsmod | grep -i bluetooth` to see whether the Bluetooth stack is loaded at all","needs_analyst":true,"not_affected_if":["no-bluetooth-hardware","bluetooth-module-not-loaded"],"who_is_affected":"Systems running a Linux kernel with the Bluetooth HCI stack enabled and in use, such as laptops, desktops and devices with Bluetooth adapters. Servers and containers without Bluetooth hardware or with the module not loaded are unlikely to be exposed. The sources do not say which kernel versions are affected.","user_interaction":"unknown","needs_special_setup":"unknown","severity_if_unknown":"unknown"},"cost_usd":0.000743,"input_tokens":4077,"output_tokens":670,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'+0':199C,214C,220C,230C,236C,246C,250C,255C,269C,283C,289C,299C,305C,315C,319C,324C '-2026':16A,19A '-98737':17A,20A '86':294C '90':225C '91':310C '93':241C 'access':185C 'achiev':72B 'acl':114C,195C,210C 'acquir':143C 'across':329C 'address':341C 'alloc':222C,291C 'also':175C 'attack':70B 'beyond':73B 'bluetooth':3A,21B,35B,84C 'bug':186C,257C 'cach':5A,41B,89C,105C,149C,178C,228C,244C,297C,313C,351C 'call':207C,277C 'cancel':170C,346C 'caught':63B 'cmd':204C,217C,274C,286C 'code':37B 'command':96C,171C,361C 'complet':364C 'concurr':139C 'conn':116C,197C,212C 'connect':165C 'copi':338C 'corrupt':13A 'crash':11A 'creat':115C,164C,196C,211C 'create-connect':163C 'cve':15A,18A 'describ':55B 'discoveri':121C,267C,281C,345C 'either':135C 'entri':52B,125C,152C,159C,352C 'evt':235C,304C 'field':129C 'fix':87C 'flush':43B,108C,147C,245C,314C 'follow':79C 'free':9A,60B,93C,150C,192C,263C 'freed':51B,158C,238C,307C 'handler':365C 'hci':36B,85C,113C,119C,194C,203C,209C,216C,226C,232C,242C,248C,252C,265C,273C,279C,285C,295C,301C,311C,317C,321C,360C 'hci0':202C,272C 'hciinquiri':140C 'hdev':99C,110C,132C,144C,327C 'hold':98C,326C 'host':28B 'inquiri':4A,40B,88C,104C,227C,233C,243C,249C,296C,302C,312C,318C 'inquiry-cach':103C 'ioctl':141C,254C,323C 'kasan':62B,182C,187C,258C 'kernel':2A,24B,34B,77C 'let':38B 'linux':1A,23B,33B,76C 'linux-kernel':22B 'list':173C 'lock':101C,111C,133C,145C,328C,356C,370C 'look':123C 'lookup':136C,331C 'may':366C 'memori':14A 'name':169C 'need':367C 'packag':25B 'pointer':353C 'prepar':161C 'race':30B,176C 'read':49B,127C,156C,334C 'releas':354C 'remot':168C,340C 'remote-name-cancel':167C 'remov':181C 'report':183C 'req':100C 'resolv':83C 'result':234C,303C,337C 'retain':349C 'return':137C 'self':27B 'self-host':26B 'send':358C 'sinc':362C 'slab':189C,260C 'slab-use-after-fre':188C,259C 'sock':253C,322C 'sourc':54B 'state':67B 'still':48B 'stop':120C,266C,280C 'sync':46B,86C,95C,117C,122C,198C,205C,213C,218C,268C,275C,282C,287C 'synchron':359C 'take':131C 'task':224C,240C,293C,309C 'trace':208C,278C 'travers':174C 'unlock':343C 'updat':106C,179C,229C,298C 'use':7A,58B,91C,109C,190C,261C 'use-after-fre':6A,57B,90C 'vulner':80C 'without':130C 'work':206C,219C,276C,288C 'worker':47B,97C,154C 'workqueu':201C,271C 'x111/0x2b0':247C 'x13c/0x290':221C 'x13e/0x2f0':316C 'x173/0x300':290C 'x269/0x5f0':256C,325C 'x2f2/0x780':251C,320C 'x3b1/0x3c0':270C,284C 'x3cb/0x560':237C,306C 'x3e6/0x7d0':231C 'x483/0x940':300C 'x5f1/0x650':200C,215C","nicknames":[],"mitigations":[],"who_affected":"Systems running a Linux kernel with the Bluetooth HCI stack enabled and in use, such as laptops, desktops and devices with Bluetooth adapters. Servers and containers without Bluetooth hardware or with the module not loaded are unlikely to be exposed. The sources do not say which kernel versions are affected.","tier":"C","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-18T16:17:27+00:00","kev":null,"cvss_vector":null,"cvss_by":null,"poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-98737","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-98737","severity":null,"published_at":"2026-10-18T16:17:27+00:00","modified_at":"2026-10-21T13:21:40+00:00","first_seen_at":"2026-10-23T21:57:16+00:00","fetched_at":"2026-10-23T22:28:56+00:00","note":null}],"documents":[],"notice":"Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}