{"id":"CVE-2026-99012","kind":"vulnerability","aliases":["CVE-2026-99012"],"related":[],"title":"Linux kernel: concurrent Bluetooth ISO connects can cause use-after-free","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: ISO: Serialize concurrent connect calls\n\niso_sock_connect() checks the socket state before taking the socket lock\nand drops the lock again before setting up a connection. Two callers can\nboth pass the admission check while the socket is open or bound.\n\nCaller A can copy its destination for route selection, then caller B can\nreplace the socket destination before A binds or connects the CIS. A\nthen uses B's destination with the route selected for its own request.\nB can also proceed after A attaches a connection and sets BT_CONNECT.\nFor deferred BIS setup, B can bind a second BIS and overwrite\niso_pi(sk)->conn, leaving the first connection's reference and conn->sk\nback-pointer stranded. Concurrent CIS connects can likewise replace the\nsocket's connection. Later teardown only detaches the current connection,\nso a callback on the old connection can race with socket release and\naccess a freed socket.\n\nKASAN reported:\n\n  BUG: KASAN: slab-use-after-free in iso_sock_hold+0xf7/0x1b0\n  Call Trace:\n   iso_sock_hold+0xf7/0x1b0\n   iso_conn_del+0x7b/0x1d0\n   iso_connect_cfm+0x186/0x16a0\n   hci_conn_failed+0x154/0x280\n   hci_abort_conn_sync+0x3dc/0x7d0\n   hci_cmd_sync_work+0x173/0x300\n\n  Allocated by task 121:\n   sk_alloc+0x2b/0x6d0\n   bt_sock_alloc+0x29/0x370\n   iso_sock_alloc.constprop.0+0x19/0x300\n   iso_sock_create+0x94/0x100\n\n  Freed by task 121:\n   kfree+0x121/0x3c0\n   __sk_destruct+0x42b/0x540\n   iso_sock_release+0x29d/0x340\n   __sock_release+0xa1/0x260\n\nCheck admission under the socket lock and mark the connect operation in\nprogress before publishing its destination. Keep that flag set across\nroute lookup and connection setup, rejecting another connect with\n-EBADFD before it can change the destination or attach a connection.\nClear the flag after either helper returns, including on failure, so a\nfailed setup can be retried.\n\nA separate flag is needed because the socket lock must be released before\nacquiring the HCI device lock, while BT_CONNECT requires an attached\nconnection. Keep the existing state transitions and the deferred CIS\ncompletion through iso_sock_recvmsg().\n\nReject an existing socket attachment in __iso_chan_add() before taking\na new reference or publishing either pointer, so every caller preserves\nthe connection association. Keep the same-socket, same-connection success\ncase for deferred CIS setup. Reject an attached socket before BIS setup\nso a reusable BIS is not claimed before the attachment is rejected.\n\nIn CIS setup, reject a different HCI connection before iso_conn_add()\nand drop the per-attempt HCI hold directly. An unowned iso_conn may still\ncarry another reference after detachment, so its destruction cannot be\nrelied on to release that hold.\n\niso_listen_bis() creates a fresh PA HCI/ISO pair under the device lock,\nso the temporary iso_conn_put() frees the ISO candidate and drops its\nHCI hold on rejection. iso_conn_ready() uses a freshly allocated,\nunpublished child with no connection, making the socket-side rejection\nunreachable.","summary":"Concurrent connect calls on a Bluetooth ISO socket in the Linux kernel can corrupt connection state, leaving a callback to touch a freed socket. The sources describe a KASAN slab-use-after-free but do not state what an attacker can achieve beyond a kernel memory fault.","severity":"unknown","cvss":null,"epss":0.00209,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["bluetooth","linux-kernel","runtime","self-hosted"],"not_affected_if":["no-bluetooth-hardware"],"how_to_check":"- `uname -r` and compare against the fixed kernel builds in the NVD entry\n- Check whether the Bluetooth ISO module is loaded with `lsmod | grep bluetooth`\n- unknown for a more specific check: the sources do not say","fix":"- Update the Linux kernel to a release that includes the upstream commit 'Bluetooth: ISO: Serialize concurrent connect calls'\n- unknown for exact fixed version numbers: the sources do not list them","status":"open","published_at":"2026-10-23T13:17:23+00:00","first_seen_at":"2026-10-23T21:57:33+00:00","triaged_at":"2026-10-25T04:55:47+00:00","updated_at":"2026-10-25T12:38:50+00:00","category":"runtime","confidence":0.5,"triage":{"at":"2026-10-25T04:55:47Z","model":"claude-haiku-5-5","output":{"fix":"- Update the Linux kernel to a release that includes the upstream commit 'Bluetooth: ISO: Serialize concurrent connect calls'\n- unknown for exact fixed version numbers: the sources do not list them","reach":"local","title":"Linux kernel: concurrent Bluetooth ISO connects can cause use-after-free","impact":"high","summary":"Concurrent connect calls on a Bluetooth ISO socket in the Linux kernel can corrupt connection state, leaving a callback to touch a freed socket. The sources describe a KASAN slab-use-after-free but do not state what an attacker can achieve beyond a kernel memory fault.","category":"runtime","nicknames":[],"who_cares":["linux-kernel","bluetooth","self-hosted"],"confidence":0.5,"needs_auth":"unknown","worst_case":"unknown; the sources show a use-after-free in kernel memory","analyst_note":"Check the NVD entry and the upstream kernel commit for affected and fixed version ranges, and whether an unprivileged local user can reach iso_sock_connect.","how_to_check":"- `uname -r` and compare against the fixed kernel builds in the NVD entry\n- Check whether the Bluetooth ISO module is loaded with `lsmod | grep bluetooth`\n- unknown for a more specific check: the sources do not say","needs_analyst":true,"not_affected_if":["no-bluetooth-hardware"],"who_is_affected":"Systems running a Linux kernel with Bluetooth ISO support (CIS and BIS connections, LE Audio class hardware) are in scope. The sources do not say whether a default build or distribution kernel enables this path, so unknown for how common exposure is. Hosts without Bluetooth hardware or with the Bluetooth stack disabled are likely unaffected.","user_interaction":"unknown","needs_special_setup":"yes","severity_if_unknown":"unknown"},"cost_usd":0.000773,"input_tokens":4400,"output_tokens":667,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'+0':255C,262C,267C,272C,277C,283C,289C,297C,302C,306C,311C,318C,322C,327C,331C '-2026':14A,17A '-99012':15A,18A '0':305C '121':294C,316C 'abort':280C 'access':238C 'achiev':69B 'acquir':405C 'across':354C 'add':439C,500C 'admiss':119C,334C 'alloc':291C,296C,301C,568C 'also':168C 'anoth':361C,517C 'associ':455C 'attach':172C,372C,415C,435C,472C,486C 'attack':67B 'attempt':506C 'b':139C,155C,166C,183C 'back':205C 'back-point':204C 'beyond':70B 'bind':147C,185C 'bis':181C,188C,475C,480C,534C 'bluetooth':4A,19B,32B,85C 'bound':127C 'bt':177C,299C,411C 'bug':244C 'call':29B,90C,257C 'callback':45B,227C 'caller':114C,128C,138C,451C 'candid':554C 'cannot':524C 'carri':516C 'case':465C 'caus':8A 'cfm':271C 'chan':438C 'chang':368C 'check':94C,120C,333C 'child':570C 'cis':151C,209C,425C,468C,490C 'claim':483C 'clear':375C 'cmd':286C 'complet':426C 'concurr':3A,27B,88C,208C 'conn':194C,202C,265C,275C,281C,499C,513C,549C,563C 'connect':6A,28B,41B,89C,93C,112C,149C,174C,178C,198C,210C,217C,224C,231C,270C,342C,358C,362C,374C,412C,416C,454C,463C,496C,573C 'copi':131C 'corrupt':40B 'creat':310C,535C 'current':223C 'cve':13A,16A 'defer':180C,424C,467C 'del':266C 'describ':53B 'destin':133C,144C,157C,349C,370C 'destruct':321C,523C 'detach':221C,520C 'devic':408C,543C 'differ':494C 'direct':509C 'drop':104C,502C,556C 'ebadfd':364C 'either':379C,447C 'everi':450C 'exist':419C,433C 'fail':276C,387C 'failur':384C 'fault':74B 'first':197C 'flag':352C,377C,394C 'follow':80C 'free':12A,60B,250C,551C 'freed':49B,240C,313C 'fresh':537C,567C 'hci':274C,279C,285C,407C,495C,507C,558C 'hci/iso':539C 'helper':380C 'hold':254C,261C,508C,531C,559C 'host':26B 'includ':382C 'iso':5A,33B,86C,91C,191C,252C,259C,264C,269C,308C,324C,428C,437C,498C,512C,532C,548C,553C,562C 'iso_sock_alloc.constprop':304C 'kasan':55B,242C,245C 'keep':350C,417C,456C 'kernel':2A,22B,38B,72B,78C 'kfree':317C 'later':218C 'leav':43B,195C 'likewis':212C 'linux':1A,21B,37B,77C 'linux-kernel':20B 'listen':533C 'lock':102C,106C,338C,400C,409C,544C 'lookup':356C 'make':574C 'mark':340C 'may':514C 'memori':73B 'must':401C 'need':396C 'new':443C 'old':230C 'open':125C 'oper':343C 'overwrit':190C 'pa':538C 'pair':540C 'pass':117C 'per':505C 'per-attempt':504C 'pi':192C 'pointer':206C,448C 'preserv':452C 'proceed':169C 'progress':345C 'publish':347C,446C 'put':550C 'race':233C 'readi':564C 'recvmsg':430C 'refer':200C,444C,518C 'reject':360C,431C,470C,488C,492C,561C,579C 'releas':236C,326C,330C,403C,529C 'reli':526C 'replac':141C,213C 'report':243C 'request':165C 'requir':413C 'resolv':84C 'retri':391C 'return':381C 'reusabl':479C 'rout':135C,160C,355C 'runtim':23B 'same-connect':461C 'same-socket':458C 'second':187C 'select':136C,161C 'self':25B 'self-host':24B 'separ':393C 'serial':87C 'set':109C,176C,353C 'setup':182C,359C,388C,469C,476C,491C 'side':578C 'sk':193C,203C,295C,320C 'slab':57B,247C 'slab-use-after-fre':56B,246C 'sock':92C,253C,260C,300C,309C,325C,329C,429C 'socket':34B,50B,96C,101C,123C,143C,215C,235C,241C,337C,399C,434C,460C,473C,577C 'socket-sid':576C 'sourc':52B 'state':42B,64B,97C,420C 'still':515C 'strand':207C 'success':464C 'sync':282C,287C 'take':99C,441C 'task':293C,315C 'teardown':219C 'temporari':547C 'touch':47B 'trace':258C 'transit':421C 'two':113C 'unown':511C 'unpublish':569C 'unreach':580C 'use':10A,58B,154C,248C,565C 'use-after-fre':9A 'vulner':81C 'work':288C 'x121/0x3c0':319C 'x154/0x280':278C 'x173/0x300':290C 'x186/0x16a0':273C 'x19/0x300':307C 'x29/0x370':303C 'x29d/0x340':328C 'x2b/0x6d0':298C 'x3dc/0x7d0':284C 'x42b/0x540':323C 'x7b/0x1d0':268C 'x94/0x100':312C 'xa1/0x260':332C 'xf7/0x1b0':256C,263C","nicknames":[],"mitigations":[],"who_affected":"Systems running a Linux kernel with Bluetooth ISO support (CIS and BIS connections, LE Audio class hardware) are in scope. The sources do not say whether a default build or distribution kernel enables this path, so unknown for how common exposure is. Hosts without Bluetooth hardware or with the Bluetooth stack disabled are likely unaffected.","tier":"C","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-23T13:17:23+00:00","kev":null,"cvss_vector":null,"cvss_by":null,"poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-99012","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-99012","severity":null,"published_at":"2026-10-23T13:17:23+00:00","modified_at":"2026-10-23T13:17:23+00:00","first_seen_at":"2026-10-23T21:57:33+00:00","fetched_at":"2026-10-23T22:29:03+00:00","note":null},{"source":"epss","external_id":"CVE-2026-99012","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-99012","severity":null,"published_at":null,"modified_at":null,"first_seen_at":"2026-10-25T12:38:50+00:00","fetched_at":"2026-10-25T12:38:50+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"}