{"id":"CVE-2026-98788","summary":"futex: Fix private hash use-after-free on resize","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nfutex: Fix private hash use-after-free on resize\n\npoll_state_synchronize_rcu(mm-\u003efutex.phash.batches) is used by\nfutex_ref_drop() to check that a grace period has passed since the\ncurrent hash was published. This relies on batches referencing a grace\nperiod which started after the hash pointer was assigned.\n\n__futex_pivot_hash() sets mmph-\u003ebatches before it replaces mmph-\u003ehash:\n\n    scoped_guard(rcu) {\n            mmph-\u003ebatches = get_state_synchronize_rcu();\n            rcu_assign_pointer(mmph-\u003ehash, new);\n    }\n\nThe scoped_guard(rcu) doesn't stop new grace periods from starting, and\nif one starts between those two assignments, futex_ref_drop() can move\nforward while a reader still holds a pointer to the old hash.\n\nFix things by setting mmph-\u003ebatches after assigning mmph-\u003ehash.  The\nscoped_guard(rcu) isn't needed, so let's drop that as well.","modified":"2026-10-20T02:31:05.354479214Z","published":"2026-10-18T15:48:24.833Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98788.json"},"references":[{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"},{"type":"WEB","url":"https://git.kernel.org/stable/c/5d5dc18b3a9ac011619b7d3af4514bf9e9b6a6af"},{"type":"WEB","url":"https://git.kernel.org/stable/c/f35e3b5784221654f9cdbd6222275a7fa203f6c3"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98788.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-98788"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"56180dd20c19e5b0fa34822997a9ac66b517e7b3"},{"fixed":"5d5dc18b3a9ac011619b7d3af4514bf9e9b6a6af"},{"fixed":"f35e3b5784221654f9cdbd6222275a7fa203f6c3"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98788.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.17.0"},{"fixed":"7.2.10"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98788.json"}}],"schema_version":"1.9.0"}