{"id":"CVE-2026-99224","kind":"vulnerability","aliases":["CVE-2026-99224"],"related":[],"title":"Linux kernel: key describe can read freed module memory and crash","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nkeys: Protect the type name while describing a key\n\nkeyctl_describe_key() must keep the key type's name alive until\nkasprintf() has consumed it. The retained key reference keeps the key\nand its description alive, but does not pin the module providing its\ntype. The name is passed to kasprintf() without holding key->sem.\n\nkvasprintf() uses the saved name pointer in two formatting passes, with\na GFP_KERNEL allocation between them. With AF_RXRPC=m, a task that\npasses View permission before type retirement can overlap a privileged\nmodule unload in this order:\n\n1. KEYCTL_DESCRIBE looks up the key, saves key->type->name in the\n   kasprintf() arguments and completes the first formatting pass.\n2. While the formatter is delayed before its second pass,\n   af_rxrpc_exit() calls unregister_key_type(), which removes the type\n   from the registry and waits for key_gc_keytype().\n3. The collector takes key->sem for writing, retypes the retained key\n   to key_type_dead and completes retirement. Unregistration and module\n   exit return, allowing free_module() to release the type and name.\n4. The formatter resumes its second pass and reads the saved name from\n   released module storage, which can fault in string().\n\nHold key->sem for reading across kasprintf(). The collector then cannot\nretype the key or complete retirement until both formatting passes have\nfinished. If retirement wins the lock first, formatting uses the core\nkey_type_dead name instead. Release the semaphore immediately after\nkasprintf(), including on allocation failure, before copying to\nuserspace.\n\nOops report as below:\n\n    BUG: unable to handle page fault for address: fffffbfff8054794\n    #PF: supervisor read access in kernel mode\n    #PF: error_code(0x0000) - not-present page\n    RIP: 0010:string+0x23f/0x470\n    Call Trace:\n     vsnprintf+0x330/0x1110","summary":"A race in the Linux kernel keyring code lets a local task read the type name of a key after its module has been unloaded, causing a kernel page fault. The sources describe it as a kernel oops in the key description path, triggered when the AF_RXRPC module is unloaded during a keyctl describe call.","severity":"high","cvss":7.0,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["af_rxrpc","infrastructure","kernel","keyctl","keyring","linux"],"not_affected_if":["af_rxrpc-not-built-as-module","af_rxrpc-not-loaded","single-user-host"],"how_to_check":"- Check whether af_rxrpc is a loadable module: `grep CONFIG_AF_RXRPC /boot/config-$(uname -r)` (=m is the affected build) and `lsmod | grep rxrpc`\n- Not affected by this path if AF_RXRPC is built in (=y) or absent.\n- Check your distro's kernel changelog for the commit above or the CVE id; `uname -r` alone cannot settle it until fixed versions are published.","fix":"Upstream fix is commit fced7238b7e80cf8aa688d5af976e4aa6e33c329 ('keys: Protect the type name while describing a key', security/keys/keyctl.c, +2 lines). Fixed stable release versions: unknown. Check your distro kernel changelog for this commit or CVE-2026-99224.","status":"open","published_at":"2026-11-02T16:17:46+00:00","first_seen_at":"2026-11-02T16:24:05+00:00","triaged_at":"2026-11-02T16:26:40+00:00","updated_at":"2026-11-02T16:29:31+00:00","category":"infrastructure","confidence":0.75,"triage":{"at":"2026-11-02T16:26:40Z","model":"claude-haiku-5-5","output":{"fix":"unknown","reach":"local","title":"Linux kernel: key describe can read freed module memory and crash","impact":"medium","summary":"A race in the Linux kernel keyring code lets a local task read the type name of a key after its module has been unloaded, causing a kernel page fault. The sources describe it as a kernel oops in the key description path, triggered when the AF_RXRPC module is unloaded during a keyctl describe call.","audience":"businesses","category":"infrastructure","nicknames":[],"who_cares":["linux","kernel","keyring","af_rxrpc"],"confidence":0.6,"fix_status":"unknown","needs_auth":"yes","worst_case":"local task causes kernel page fault; denial of service","analyst_note":"Fixed kernel versions and stable backport commits are not in the sources; check the NVD record and kernel.org stable advisories for the patched release.","how_to_check":"- Check whether the kernel is built with `CONFIG_AF_RXRPC=m` or loads `af_rxrpc` as a module, e.g. `lsmod | grep rxrpc`\n- Compare the running kernel to the fixed versions listed in the NVD record: `uname -r`","plain_action":"","needs_analyst":true,"not_affected_if":["af_rxrpc-not-loaded","single-user-host"],"who_is_affected":"Systems running a Linux kernel where AF_RXRPC is built as a loadable module. The sources describe a local race that needs a task with key view permission and a privileged module unload, so exposure is limited to shared or multi-user Linux hosts. Systems with AF_RXRPC built in, or without it, are not described as affected.","user_interaction":"no","needs_special_setup":"yes","severity_if_unknown":"unknown"},"cost_usd":0.000771,"input_tokens":4684,"output_tokens":605,"severity_before":"high"},"analyst_status":"done","analyst_note":"Fixed kernel versions and stable backport commits are not in the sources; check the NVD record and kernel.org stable advisories for the patched release.","search":"'+0':373C,378C '-2026':13A,16A '-99224':14A,17A '0010':371C '0x0000':365C '1':185C '2':206C '3':236C '4':269C 'access':358C 'across':295C 'address':353C 'af':18B,71B,164C,216C 'aliv':110C,126C 'alloc':160C,336C 'allow':260C 'argument':199C 'bug':346C 'call':80B,219C,375C 'cannot':300C 'caus':50B 'code':32B,364C 'collector':238C,298C 'complet':201C,253C,305C 'consum':114C 'copi':339C 'core':322C 'crash':11A 'cve':12A,15A 'dead':251C,325C 'delay':211C 'describ':4A,57B,79B,97C,101C,187C 'descript':66B,125C 'error':363C 'exit':218C,258C 'failur':337C 'fault':54B,287C,351C 'fffffbfff8054794':354C 'finish':312C 'first':203C,318C 'follow':86C 'format':154C,204C,309C,319C 'formatt':209C,271C 'free':261C 'freed':7A 'gc':234C 'gfp':158C 'handl':349C 'hold':143C,290C 'immedi':331C 'includ':334C 'infrastructur':20B 'instead':327C 'kasprintf':112C,141C,198C,296C,333C 'keep':104C,120C 'kernel':2A,21B,30B,52B,61B,84C,159C,360C 'key':3A,43B,65B,91C,99C,102C,106C,118C,122C,144C,191C,193C,221C,233C,240C,247C,249C,291C,303C,323C 'keyctl':22B,78B,100C,186C 'keyr':23B,31B 'keytyp':235C 'kvasprintf':146C 'let':33B 'linux':1A,24B,29B,83C 'local':35B 'lock':317C 'look':188C 'm':166C 'memori':9A 'mode':361C 'modul':8A,46B,73B,132C,180C,257C,262C,283C 'must':103C 'name':40B,95C,109C,137C,150C,195C,268C,280C,326C 'not-pres':366C 'oop':62B,342C 'order':184C 'overlap':177C 'page':53B,350C,369C 'pass':139C,155C,170C,205C,215C,275C,310C 'path':67B 'permiss':172C 'pf':355C,362C 'pin':130C 'pointer':151C 'present':368C 'privileg':179C 'protect':92C 'provid':133C 'race':26B 'read':6A,37B,277C,294C,357C 'refer':119C 'registri':229C 'releas':264C,282C,328C 'remov':224C 'report':343C 'resolv':90C 'resum':272C 'retain':117C,246C 'retir':175C,254C,306C,314C 'return':259C 'retyp':244C,301C 'rip':370C 'rxrpc':19B,72B,165C,217C 'save':149C,192C,279C 'second':214C,274C 'sem':145C,241C,292C 'semaphor':330C 'sourc':56B 'storag':284C 'string':289C,372C 'supervisor':356C 'take':239C 'task':36B,168C 'trace':376C 'trigger':68B 'two':153C 'type':39B,94C,107C,135C,174C,194C,222C,226C,250C,266C,324C 'unabl':347C 'unload':49B,75B,181C 'unregist':220C 'unregistr':255C 'use':147C,320C 'userspac':341C 'view':171C 'vsnprintf':377C 'vulner':87C 'wait':231C 'win':315C 'without':142C 'write':243C 'x23f/0x470':374C 'x330/0x1110':379C","nicknames":[],"mitigations":[],"who_affected":"Linux kernels built with AF_RXRPC=m. A local task with View permission on a key must race a privileged unload of the af_rxrpc module during keyctl describe, so it needs local access and root-level module unloading; the result is a kernel oops (crash) from reading freed module memory. Hosts where af_rxrpc is built in or not present, and single-user machines that never unload modules, can skip it.","tier":"B","verified":{},"analyst_revisit_at":null,"fix_status":"unknown","audience":"businesses","plain_action":null,"pkeys":[],"ptokens":[],"labels":["afrxrpc","high","infrastructure","kernel","keyctl","keyring","linux"],"first_public_at":"2026-11-02T16:17:46+00:00","kev":null,"cvss_vector":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H","cvss_by":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-99224","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-99224","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},{"source":"analyst","external_id":"CVE-2026-99224:1396","url":null,"severity":null,"published_at":"2026-11-02T16:29:31+00:00","modified_at":"2026-11-02T16:29:31+00:00","first_seen_at":"2026-11-02T16:29:31+00:00","fetched_at":"2026-11-02T16:29:31+00:00","note":"Read the upstream fix commit fced7238b7 (Cen Zhang, reviewed by Jarkko Sakkinen, Cc stable, 2026-10-09): holds key->sem for read across kasprintf() in keyctl_describe_key(). Fixed release numbers and stable backport commits are NOT in the sources I found; NVD page fetch returned empty. Nothing marked verified: the commit is a mirror (upd.dev), not kernel.org."}],"documents":[{"id":52863,"url":"https://upd.dev/torvalds/linux/commit/fced7238b7e80cf8aa688d5af976e4aa6e33c329","title":"keys: Protect the type name while describing a key (fced7238b7)","kind":"release","source":"analyst","publisher":null,"text":null,"published_at":null,"relation":"fix","confidence":null,"note":null},{"id":52864,"url":"https://lkml.iu.edu/2610.1/02319.html","title":"Re: [PATCH] keys: Protect the type name while describing a key (LKML)","kind":"issue","source":"analyst","publisher":null,"text":null,"published_at":null,"relation":"discussion","confidence":null,"note":null},{"id":52865,"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-99224","title":"NVD CVE-2026-99224","kind":"other","source":"analyst","publisher":null,"text":null,"published_at":null,"relation":"describes","confidence":null,"note":null}],"notice":"Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}