{"id":"CVE-2026-99222","kind":"vulnerability","aliases":["CVE-2026-99222"],"related":[],"title":"Linux kernel: key read races module unload, risking freed-memory access","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nkeys: Protect the read method check against type removal\n\nkeyctl_read_key() checks key->type->read without holding key->sem.\nA reference keeps the key alive, but does not pin the module containing\nits type. A surviving RxRPC key can therefore be read while AF_RXRPC\nis being unloaded:\n\n  KEYCTL_READ task                    Module unload and key GC\n  ----------------                   ------------------------\n  lookup_user_key()\n  permission / possession checks\n  load key->type\n                                     af_rxrpc_exit()\n                                       unregister_key_type()\n                                         GC: down_write(key->sem)\n                                         GC: retype to key_type_dead\n                                         GC: up_write(key->sem)\n                                       unregister_key_type() returns\n                                     free_module()\n  read saved type's read member\n\nThe final access can read freed module storage. The read invocation in\n__keyctl_read_key() is already protected by key->sem, but the earlier\nmethod check is outside that critical section.\n\nMove the method check into __keyctl_read_key(), after key_validate() and\nunder its existing read hold on key->sem. The check and invocation then\nuse the same protected type for length queries and every read retry.\nThe GC cannot retype the key until the semaphore is released, and type\nunregistration waits for that GC pass before the module can be freed.\n\nReturn -EOPNOTSUPP when validation succeeds and the type has no read\nmethod. A temporary buffer may now be allocated before this result;\nallocation and copying to userspace remain outside the semaphore.","summary":"The Linux kernel's keyctl read path checks a key type's read method outside the lock that protects it, so a key can be read while the RxRPC module is being unloaded. The sources describe this as reading freed module memory, which can crash the system or be abused locally.","severity":"unknown","cvss":null,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["kernel","linux","runtime","rxrpc"],"not_affected_if":["rxrpc-not-loaded"],"how_to_check":"- Run `uname -r` and compare against the fixed kernel versions in the upstream stable tree (not stated in the sources)\n- Check whether the AF_RXRPC module is loaded with `lsmod | grep rxrpc`","fix":null,"status":"open","published_at":"2026-11-02T16:17:46+00:00","first_seen_at":"2026-11-02T16:24:05+00:00","triaged_at":"2026-11-02T16:26:58+00:00","updated_at":"2026-11-02T16:26:58+00:00","category":"runtime","confidence":0.55,"triage":{"at":"2026-11-02T16:26:58Z","model":"claude-haiku-5-5","output":{"fix":"unknown","reach":"local","title":"Linux kernel: key read races module unload, risking freed-memory access","impact":"medium","summary":"The Linux kernel's keyctl read path checks a key type's read method outside the lock that protects it, so a key can be read while the RxRPC module is being unloaded. The sources describe this as reading freed module memory, which can crash the system or be abused locally.","audience":"businesses","category":"runtime","nicknames":[],"who_cares":["linux","kernel","rxrpc"],"confidence":0.55,"fix_status":"unknown","needs_auth":"yes","worst_case":"local user reads freed kernel module memory, possibly crashing or escalating","analyst_note":"Find the fixed kernel versions and stable backport commits for the keys method-check change from the kernel.org CVE record.","how_to_check":"- Run `uname -r` and compare against the fixed kernel versions in the upstream stable tree (not stated in the sources)\n- Check whether the AF_RXRPC module is loaded with `lsmod | grep rxrpc`","plain_action":"","needs_analyst":true,"not_affected_if":["rxrpc-not-loaded"],"who_is_affected":"Only systems where the RxRPC key type is present and AF_RXRPC can be unloaded are described as relevant; the sources do not say more. Systems that do not load the rxrpc module are likely not affected, but the sources do not confirm this.","user_interaction":"no","needs_special_setup":"yes","severity_if_unknown":"unknown"},"cost_usd":0.000718,"input_tokens":4530,"output_tokens":530,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-2026':14A,17A '-99222':15A,18A 'abus':72B 'access':12A,186C 'af':128C,150C 'aliv':109C 'alloc':295C,299C 'alreadi':200C 'buffer':291C 'cannot':254C 'check':30B,89C,96C,146C,209C,218C,236C 'contain':116C 'copi':301C 'crash':67B 'critic':213C 'cve':13A,16A 'dead':166C 'describ':58B 'earlier':207C 'eopnotsupp':278C 'everi':249C 'exist':229C 'exit':152C 'final':185C 'follow':79C 'free':176C 'freed':10A,62B,189C,276C 'freed-memori':9A 'gc':140C,156C,161C,167C,253C,269C 'hold':101C,231C 'invoc':194C,238C 'keep':106C 'kernel':2A,19B,25B,77C 'key':3A,32B,45B,84C,95C,97C,102C,108C,122C,139C,143C,148C,154C,159C,164C,170C,173C,198C,203C,222C,224C,233C,257C 'keyctl':27B,93C,133C,196C,220C 'length':246C 'linux':1A,20B,24B,76C 'load':147C 'local':73B 'lock':39B 'lookup':141C 'may':292C 'member':183C 'memori':11A,64B 'method':36B,88C,208C,217C,288C 'modul':6A,52B,63B,115C,136C,177C,190C,273C 'move':215C 'outsid':37B,211C,305C 'pass':270C 'path':29B 'permiss':144C 'pin':113C 'possess':145C 'protect':41B,85C,201C,243C 'queri':247C 'race':5A 'read':4A,28B,35B,48B,61B,87C,94C,99C,126C,134C,178C,182C,188C,193C,197C,221C,230C,250C,287C 'refer':105C 'releas':262C 'remain':304C 'remov':92C 'resolv':83C 'result':298C 'retri':251C 'return':175C,277C 'retyp':162C,255C 'risk':8A 'runtim':21B 'rxrpc':22B,51B,121C,129C,151C 'save':179C 'section':214C 'sem':103C,160C,171C,204C,234C 'semaphor':260C,307C 'sourc':57B 'storag':191C 'succeed':281C 'surviv':120C 'system':69B 'task':135C 'temporari':290C 'therefor':124C 'type':33B,91C,98C,118C,149C,155C,165C,174C,180C,244C,264C,284C 'unload':7A,55B,132C,137C 'unregist':153C,172C 'unregistr':265C 'use':240C 'user':142C 'userspac':303C 'valid':225C,280C 'vulner':80C 'wait':266C 'without':100C 'write':158C,169C","nicknames":[],"mitigations":[],"who_affected":"Only systems where the RxRPC key type is present and AF_RXRPC can be unloaded are described as relevant; the sources do not say more. Systems that do not load the rxrpc module are likely not affected, but the sources do not confirm this.","tier":"C","verified":{},"analyst_revisit_at":null,"fix_status":"unknown","audience":"businesses","plain_action":null,"pkeys":[],"ptokens":[],"labels":["kernel","linux","runtime","rxrpc","unknown"],"first_public_at":"2026-11-02T16:17:46+00:00","kev":null,"cvss_vector":null,"cvss_by":null,"poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-99222","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-99222","severity":null,"published_at":"2026-11-02T16:17:46+00:00","modified_at":"2026-11-02T16:17:46+00:00","first_seen_at":"2026-11-02T16:24:05+00:00","fetched_at":"2026-11-02T16:24:05+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"}