{"id":"CVE-2026-98994","kind":"vulnerability","aliases":["CVE-2026-98994"],"related":[],"title":"Linux kernel: statmount reads freed parent mount, causing use-after-free","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nstatmount: read the parent of an unmounted mount under mount_lock\n\nstatmount_mnt_basic() reads the ids of the parent through m->mnt_parent\nwith namespace_sem held for reading. That's fine for a mount that is\nin a namespace. Everything above it is pinned by that namespace.\n\nSTATMOUNT_BY_FD also accepts a file descriptor on a mount that has\nbeen unmounted on purpose and that only the file descriptor keeps alive.\nIf that mount stayed attached to its parent when it was unmounted the\nparent is unmounted as well and nothing pins it for the child.\n\nThe final mntput() unmounts the children under mount_lock alone and\nfrees the parent afterwards. Concurrently, statmount_mnt_basic() reads\nm->mnt_parent twice while that can happen and can easily dereference a\nmount that's already gone.\n\nRead the parent of an unmounted mount under mount_lock. The parent\ncan't be put while it is held and both ids come from the same mount. A\nmounted mount's parent is pinned by the namespace and a mount can't\nleave its namespace while namespace_sem is held, so the common case\ntakes no global lock.","summary":"In the Linux kernel's statmount path, a file descriptor on an unmounted mount can cause the parent mount to be read after it has been freed. The sources describe a race where an attacker-reachable call dereferences a dangling pointer, but they do not state the resulting impact beyond a memory-safety bug.","severity":"unknown","cvss":null,"epss":0.00198,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["linux-kernel","other"],"not_affected_if":[],"how_to_check":"- unknown","fix":"- unknown","status":"open","published_at":"2026-10-23T13:17:21+00:00","first_seen_at":"2026-10-23T21:57:33+00:00","triaged_at":"2026-10-25T04:56:02+00:00","updated_at":"2026-10-25T12:38:50+00:00","category":"other","confidence":0.5,"triage":{"at":"2026-10-25T04:56:02Z","model":"claude-haiku-5-5","output":{"fix":"- unknown","reach":"local","title":"Linux kernel: statmount reads freed parent mount, causing use-after-free","impact":"medium","summary":"In the Linux kernel's statmount path, a file descriptor on an unmounted mount can cause the parent mount to be read after it has been freed. The sources describe a race where an attacker-reachable call dereferences a dangling pointer, but they do not state the resulting impact beyond a memory-safety bug.","category":"other","nicknames":[],"who_cares":["linux-kernel"],"confidence":0.5,"needs_auth":"unknown","worst_case":"unknown","analyst_note":"Find the kernel commit or stable backport that fixes statmount_mnt_basic(), the affected kernel version range, and whether an unprivileged user can reach STATMOUNT_BY_FD. Source: https://nvd.nist.gov/vuln/detail/CVE-2026-98994","how_to_check":"- unknown","needs_analyst":true,"not_affected_if":[],"who_is_affected":"unknown","user_interaction":"unknown","needs_special_setup":"unknown","severity_if_unknown":"unknown"},"cost_usd":0.000563,"input_tokens":3612,"output_tokens":404,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-2026':14A,17A '-98994':15A,18A 'accept':141C 'afterward':201C 'aliv':161C 'alon':196C 'alreadi':223C 'also':140C 'attach':166C 'attack':57B 'attacker-reach':56B 'basic':101C,205C 'beyond':72B 'bug':77B 'call':59B 'case':279C 'caus':8A,37B 'child':186C 'children':192C 'come':248C 'common':278C 'concurr':202C 'cve':13A,16A 'dangl':62B 'derefer':60B,218C 'describ':51B 'descriptor':31B,144C,159C 'easili':217C 'everyth':129C 'fd':139C 'file':30B,143C,158C 'final':188C 'fine':120C 'follow':83C 'free':12A,198C 'freed':5A,48B 'global':282C 'gone':224C 'happen':214C 'held':115C,244C,275C 'id':104C,247C 'impact':71B 'keep':160C 'kernel':2A,21B,25B,81C 'leav':268C 'linux':1A,20B,24B,80C 'linux-kernel':19B 'lock':98C,195C,234C,283C 'm':109C,207C 'memori':75B 'memory-safeti':74B 'mnt':100C,110C,204C,208C 'mntput':189C 'mount':7A,35B,40B,95C,97C,123C,147C,164C,194C,220C,231C,233C,252C,254C,255C,265C 'namespac':113C,128C,136C,262C,270C,272C 'noth':181C 'parent':6A,39B,91C,107C,111C,169C,175C,200C,209C,227C,236C,257C 'path':28B 'pin':133C,182C,259C 'pointer':63B 'purpos':153C 'put':240C 'race':53B 'reachabl':58B 'read':4A,43B,89C,102C,117C,206C,225C 'resolv':87C 'result':70B 'safeti':76B 'sem':114C,273C 'sourc':50B 'state':68B 'statmount':3A,27B,88C,99C,137C,203C 'stay':165C 'take':280C 'twice':210C 'unmount':34B,94C,151C,173C,177C,190C,230C 'use':10A 'use-after-fre':9A 'vulner':84C 'well':179C","nicknames":[],"mitigations":[],"who_affected":null,"tier":"C","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-23T13:17:21+00:00","kev":null,"cvss_vector":null,"cvss_by":null,"poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-98994","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-98994","severity":null,"published_at":"2026-10-23T13:17:21+00:00","modified_at":"2026-10-23T13:17:21+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-2026-98994","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-98994","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"}