{"id":"CVE-2026-99223","kind":"vulnerability","aliases":["CVE-2026-99223"],"related":[],"title":"Linux kernel: keyring order leaks kernel addresses, weakening KASLR","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nkeys: make keyring indexes independent of kernel addresses\n\nKEYCTL_READ returns the serial numbers in a keyring in associative-array\ntraversal order.  The first word of the index is a public, deterministic\nhash of the type pointer, domain pointer and description.  An unprivileged\nuser can therefore insert keys with known descriptions, predict their\norder for each possible KASLR slide, and recover the kernel image address.\nOn an x86-64 build with 16 MiB alignment, 45 user keys suffice to\ndistinguish the candidate slides.\n\nRemove the addresses from the whole index, not just its first hash word.\nAssign each key type and domain a nonzero 64-bit ID and hash those IDs and\nthe description with a once-initialized SipHash key.  Use the full IDs in\nthe later index chunks as well.  Truncating or hashing the IDs there would\nlose the guarantee that distinct type/domain/description tuples have a\ndiffering index bit.\n\nAllocate IDs lazily since private key types need not be registered.  Cache\nthem in the index key so tree walks and copies of an existing index do not\nneed to dereference a type descriptor that may have been unregistered.\nKeep the 32-bit chunk layout and diff_objects() bit offsets consistent,\nand retain the separate root slot for keyrings used by recursive search.\nThe key comparison, permissions and userspace data format are unchanged;\nonly the address-dependent in-memory ordering is replaced.","summary":"The Linux kernel's keyring index ordering depended on kernel memory addresses, so the order returned by KEYCTL_READ could reveal the kernel's randomized load address. An unprivileged local user could use this to defeat KASLR, making other kernel exploits easier.","severity":"low","cvss":null,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["linux-kernel","multi-user-systems","runtime","self-hosted"],"not_affected_if":["single-user-machines"],"how_to_check":null,"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":0.6,"triage":{"at":"2026-11-02T16:26:58Z","model":"claude-haiku-5-5","output":{"fix":"unknown","reach":"local","title":"Linux kernel: keyring order leaks kernel addresses, weakening KASLR","impact":"low","summary":"The Linux kernel's keyring index ordering depended on kernel memory addresses, so the order returned by KEYCTL_READ could reveal the kernel's randomized load address. An unprivileged local user could use this to defeat KASLR, making other kernel exploits easier.","audience":"businesses","category":"runtime","nicknames":[],"who_cares":["linux-kernel","self-hosted","multi-user-systems"],"confidence":0.6,"fix_status":"unknown","needs_auth":"yes","worst_case":"local user recovers kernel address, aiding further kernel exploits","analyst_note":"Find the fixed kernel versions and stable commit references from the NVD entry at https://nvd.nist.gov/vuln/detail/CVE-2026-99223.","how_to_check":"- unknown","plain_action":"","needs_analyst":true,"not_affected_if":["single-user-machines"],"who_is_affected":"Affects Linux systems with the kernel keyring subsystem in use, where local unprivileged users can create keys and call KEYCTL_READ. The sources describe an x86-64 build with 16 MiB KASLR alignment. Systems that do not expose local untrusted users have less exposure. Sources do not give affected kernel version ranges.","user_interaction":"no","needs_special_setup":"unknown","severity_if_unknown":"low"},"cost_usd":0.00071,"input_tokens":4514,"output_tokens":518,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-2026':11A,14A '-64':148C '-99223':12A,15A '16':151C '32':272C '45':154C '64':184C 'address':7A,38B,53B,86C,144C,165C,307C 'address-depend':306C 'align':153C 'alloc':231C 'array':99C 'assign':176C 'associ':98C 'associative-array':97C 'bit':185C,230C,273C,279C 'build':149C 'cach':242C 'candid':161C 'chunk':209C,274C 'comparison':296C 'consist':281C 'copi':252C 'could':46B,58B 'cve':10A,13A 'data':300C 'defeat':62B 'depend':34B,308C 'derefer':261C 'descript':120C,130C,193C 'descriptor':264C 'determinist':111C 'diff':277C 'differ':228C 'distinct':223C 'distinguish':159C 'domain':117C,181C 'easier':68B 'exist':255C 'exploit':67B 'first':103C,173C 'follow':74C 'format':301C 'full':203C 'guarante':221C 'hash':112C,174C,188C,214C 'host':26B 'id':186C,190C,204C,216C,232C 'imag':143C 'in-memori':309C 'independ':83C 'index':32B,82C,107C,169C,208C,229C,246C,256C 'initi':198C 'insert':126C 'kaslr':9A,63B,137C 'keep':270C 'kernel':2A,6A,18B,29B,36B,49B,66B,72C,85C,142C 'key':79C,127C,156C,178C,200C,236C,247C,295C 'keyctl':44B,87C 'keyr':3A,31B,81C,95C,289C 'known':129C 'later':207C 'layout':275C 'lazili':233C 'leak':5A 'linux':1A,17B,28B,71C 'linux-kernel':16B 'load':52B 'local':56B 'lose':219C 'make':64B,80C 'may':266C 'memori':37B,311C 'mib':152C 'multi':20B 'multi-user-system':19B 'need':238C,259C 'nonzero':183C 'number':92C 'object':278C 'offset':280C 'once-initi':196C 'order':4A,33B,41B,101C,133C,312C 'permiss':297C 'pointer':116C,118C 'possibl':136C 'predict':131C 'privat':235C 'public':110C 'random':51B 'read':45B,88C 'recov':140C 'recurs':292C 'regist':241C 'remov':163C 'replac':314C 'resolv':78C 'retain':283C 'return':42B,89C 'reveal':47B 'root':286C 'runtim':23B 'search':293C 'self':25B 'self-host':24B 'separ':285C 'serial':91C 'sinc':234C 'siphash':199C 'slide':138C,162C 'slot':287C 'suffic':157C 'system':22B 'therefor':125C 'travers':100C 'tree':249C 'truncat':212C 'tupl':225C 'type':115C,179C,237C,263C 'type/domain/description':224C 'unchang':303C 'unprivileg':55B,122C 'unregist':269C 'use':59B,201C,290C 'user':21B,57B,123C,155C 'userspac':299C 'vulner':75C 'walk':250C 'weaken':8A 'well':211C 'whole':168C 'word':104C,175C 'would':218C 'x86':147C","nicknames":[],"mitigations":[],"who_affected":"Affects Linux systems with the kernel keyring subsystem in use, where local unprivileged users can create keys and call KEYCTL_READ. The sources describe an x86-64 build with 16 MiB KASLR alignment. Systems that do not expose local untrusted users have less exposure. Sources do not give affected kernel version ranges.","tier":"C","verified":{},"analyst_revisit_at":null,"fix_status":"unknown","audience":"businesses","plain_action":null,"pkeys":[],"ptokens":[],"labels":["linuxkernel","low","multiusersystems","runtime","selfhosted"],"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-2026-99223","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-99223","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"}