{"id":"CVE-2026-99134","kind":"vulnerability","aliases":["CVE-2026-99134"],"related":[],"title":"Linux kernel: mac802154 association race can cause a NULL dereference","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nmac802154: fix data race and NULL deref on local->assoc_dev\n\nlocal->assoc_dev is shared between the association path and the\nassociation-response worker without common synchronization.\n\nmac802154_perform_association() stores the coordinator pointer and waits\nfor a response. Its timeout and error paths clear the pointer and return\nto mac802154_associate(), which may then free the coordinator object.\nMeanwhile, mac802154_rx_mac_cmd_worker() may observe the associating bit\nand enter mac802154_process_association_resp(), which dereferences\nassoc_dev.\n\nThe worker's bit test and the handler's pointer dereference are not\natomic with respect to cleanup. Cleanup can clear assoc_dev between them,\ncausing a NULL dereference, or free the coordinator while the response\nhandler still uses the pointer.\n\nThe recorded result is exposed to the same window. assoc_status and\nassoc_addr are written by the handler but read by the association path\nwhile the associating bit is still set, so a second response for the same\nrequest - a malicious one, for instance - can replace them between those\nreads and leave the caller with an incoherent status and address pair.\n\nThe response handler only needs the coordinator extended address.\nReplace assoc_dev with a cached address, removing the pointer lifetime\ndependency. Protect the cached address and the associating bit with a\ndedicated spinlock. A READ_ONCE()/WRITE_ONCE() pair would not guarantee\nan atomic __le64 access on all 32-bit architectures.\n\nwpan_dev->association_lock cannot be reused here: nl802154_associate()\nholds it across rdev_associate(), hence for the whole of\nmac802154_perform_association() including the wait for the response.\nA response handler taking that lock would only get it once the\nassociation has already given up.\n\nReset the completion, publish the cached address, and set the associating\nbit while holding the lock. The response handler takes the lock, rechecks\nthe bit and the cached address, records the response, clears the bit, and\nonly then completes the waiter. Thus cleanup cannot pass the handler\nbetween its state check and completion, and the cached 64-bit value\ncannot tear.\n\nThe handler clears the bit before completing, not the woken waiter:\notherwise complete() is issued under the lock and a second (e.g.\nmalicious) response can reacquire it before the waiter and replace the\nresult. So a wait that returns success implies the bit is already clear,\nand the success and negative-response paths return directly. The\ntransmit-error and timeout paths still clear it under assoc_lock, which\nserializes any racing response against the cleanup while the call returns\nthe error it already selected. Both paths snapshot assoc_status and\nassoc_addr under the same lock.\n\nBoth users run in process context, so a plain spinlock is sufficient.\nThe lock is not held while waiting for the completion.","summary":"A race in the Linux kernel's mac802154 (IEEE 802.15.4) association code lets the association response worker use a coordinator pointer that cleanup has already cleared or freed, causing a NULL dereference or use-after-free. The fix replaces the shared pointer with a cached address protected by a spinlock.","severity":"unknown","cvss":null,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["embedded","ieee-802.15.4","linux-kernel","runtime"],"not_affected_if":["module-not-loaded","no-802.15.4-hardware"],"how_to_check":"- Check the running kernel version with `uname -r` and compare it against the fixed stable release listed in the NVD entry\n- Check whether the mac802154 module is loaded with `lsmod | grep mac802154`","fix":"- Update the Linux kernel to a release that includes the mac802154 association fix (the sources do not list the fixed version numbers)\n- Unknown whether a configuration change can disable the affected code path","status":"open","published_at":"2026-10-28T11:17:33+00:00","first_seen_at":"2026-10-28T11:32:35+00:00","triaged_at":"2026-10-28T11:36:14+00:00","updated_at":"2026-10-28T11:36:14+00:00","category":"runtime","confidence":0.5,"triage":{"at":"2026-10-28T11:36:14Z","model":"claude-haiku-5-5","output":{"fix":"- Update the Linux kernel to a release that includes the mac802154 association fix (the sources do not list the fixed version numbers)\n- Unknown whether a configuration change can disable the affected code path","reach":"local","title":"Linux kernel: mac802154 association race can cause a NULL dereference","impact":"medium","summary":"A race in the Linux kernel's mac802154 (IEEE 802.15.4) association code lets the association response worker use a coordinator pointer that cleanup has already cleared or freed, causing a NULL dereference or use-after-free. The fix replaces the shared pointer with a cached address protected by a spinlock.","category":"runtime","nicknames":[],"who_cares":["linux-kernel","ieee-802.15.4","embedded"],"confidence":0.5,"needs_auth":"unknown","worst_case":"Kernel NULL dereference or use-after-free during association handling","analyst_note":"Check the NVD entry and the kernel stable commit for fixed versions and whether a remote peer can trigger the second response.","how_to_check":"- Check the running kernel version with `uname -r` and compare it against the fixed stable release listed in the NVD entry\n- Check whether the mac802154 module is loaded with `lsmod | grep mac802154`","needs_analyst":true,"not_affected_if":["no-802.15.4-hardware","module-not-loaded"],"who_is_affected":"Systems that load the mac802154 module for IEEE 802.15.4 low-rate wireless networking, such as some Zigbee or 6LoWPAN setups. Machines that do not use 802.15.4 hardware or do not load this module are unlikely to be exposed; the sources do not say more.","user_interaction":"no","needs_special_setup":"unknown","severity_if_unknown":"unknown"},"cost_usd":0.000723,"input_tokens":4150,"output_tokens":616,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-2026':12A,15A '-99134':13A,16A '/write_once':306C '32':317C '64':422C '802.15.4':19B,33B 'access':314C 'across':332C 'addr':221C,520C 'address':70B,268C,278C,285C,294C,372C,394C 'alreadi':48B,363C,471C,511C 'architectur':319C 'assoc':94C,97C,165C,188C,217C,220C,280C,494C,516C,519C 'associ':4A,34B,38B,103C,108C,116C,138C,155C,161C,231C,235C,297C,322C,329C,334C,342C,361C,376C 'association-respons':107C 'atom':180C,312C 'bit':156C,170C,236C,298C,318C,377C,390C,400C,423C,431C,469C 'cach':69B,284C,293C,371C,393C,421C 'call':506C 'caller':262C 'cannot':324C,409C,425C 'caus':7A,52B,192C 'check':416C 'cleanup':46B,184C,185C,408C,503C 'clear':49B,131C,187C,398C,429C,472C,491C 'cmd':150C 'code':35B 'common':112C 'complet':368C,404C,418C,433C,439C,546C 'context':530C 'coordin':43B,119C,144C,199C,276C 'cve':11A,14A 'data':87C 'dedic':301C 'depend':290C 'deref':91C 'derefer':10A,55B,164C,177C,195C 'dev':95C,98C,166C,189C,281C,321C 'direct':482C 'e.g':448C 'embed':17B 'enter':158C 'error':129C,486C,509C 'expos':212C 'extend':277C 'fix':62B,86C 'follow':80C 'free':60B,142C,197C 'freed':51B 'get':357C 'given':364C 'guarante':310C 'handler':174C,203C,226C,272C,351C,384C,412C,428C 'held':541C 'henc':335C 'hold':330C,379C 'ieee':18B,32B 'impli':467C 'includ':343C 'incoher':265C 'instanc':252C 'issu':441C 'kernel':2A,22B,29B,78C 'le64':313C 'leav':260C 'let':36B 'lifetim':289C 'linux':1A,21B,28B,77C 'linux-kernel':20B 'local':93C,96C 'lock':323C,354C,381C,387C,444C,495C,524C,538C 'mac':149C 'mac802154':3A,31B,85C,114C,137C,147C,159C,340C 'malici':249C,449C 'may':140C,152C 'meanwhil':146C 'need':274C 'negat':478C 'negative-respons':477C 'nl802154':328C 'null':9A,54B,90C,194C 'object':145C 'observ':153C 'one':250C 'otherwis':438C 'pair':269C,307C 'pass':410C 'path':104C,130C,232C,480C,489C,514C 'perform':115C,341C 'plain':533C 'pointer':44B,66B,120C,133C,176C,207C,288C 'process':160C,529C 'protect':71B,291C 'publish':369C 'race':5A,25B,88C,499C 'rdev':333C 'reacquir':452C 'read':228C,258C,304C 'recheck':388C 'record':209C,395C 'remov':286C 'replac':63B,254C,279C,458C 'request':247C 'reset':366C 'resolv':84C 'resp':162C 'respect':182C 'respons':39B,109C,125C,202C,243C,271C,348C,350C,383C,397C,450C,479C,500C 'result':210C,460C 'return':135C,465C,481C,507C 'reus':326C 'run':527C 'runtim':23B 'rx':148C 'second':242C,447C 'select':512C 'serial':497C 'set':239C,374C 'share':65B,100C 'snapshot':515C 'spinlock':74B,302C,534C 'state':415C 'status':218C,266C,517C 'still':204C,238C,490C 'store':117C 'success':466C,475C 'suffici':536C 'synchron':113C 'take':352C,385C 'tear':426C 'test':171C 'thus':407C 'timeout':127C,488C 'transmit':485C 'transmit-error':484C 'use':41B,58B,205C 'use-after-fre':57B 'user':526C 'valu':424C 'vulner':81C 'wait':122C,345C,463C,543C 'waiter':406C,437C,456C 'whole':338C 'window':216C 'without':111C 'woken':436C 'worker':40B,110C,151C,168C 'would':308C,355C 'wpan':320C 'written':223C","nicknames":[],"mitigations":[],"who_affected":"Systems that load the mac802154 module for IEEE 802.15.4 low-rate wireless networking, such as some Zigbee or 6LoWPAN setups. Machines that do not use 802.15.4 hardware or do not load this module are unlikely to be exposed; the sources do not say more.","tier":"C","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-28T11:17:33+00:00","kev":null,"cvss_vector":null,"cvss_by":null,"poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-99134","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-99134","severity":null,"published_at":"2026-10-28T11:17:33+00:00","modified_at":"2026-10-28T11:17:33+00:00","first_seen_at":"2026-10-28T11:32:35+00:00","fetched_at":"2026-10-28T11:32:35+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"}