{"schema":"threatline.record/2","record":{"id":"CVE-2026-98866","aliases":[],"summary":"sched/cache: Introduce task_struct->sched_cache_grp to fix UAF","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nsched/cache: Introduce task_struct->sched_cache_grp to fix UAF\n\nAdd a sched_cache_grp pointer to task_struct so that scheduler code\ncan access the cache group directly via the task, without going\nthrough mm->sched_cache_grp.  This decouples the scheduler's hot-path\naccesses from the mm_struct.\n\nEach task holds its own refcount on the sched_cache_group, separate\nfrom the reference held by its mm_struct.  The reference is acquired\nin copy_mm() (fork) and exec_mmap() (exec), and released in exit_mm().\nThis fixes the use-after-free when account_mm_sched() reaches the group\nthrough a task whose mm is being switched, as reported by Hyunwoo:\n\n  https://lore.kernel.org/lkml/apPb-Dr4nPYuHQOK@v4bel/\n\nConvert all scheduler code in fair.c and exit.c to use\np->sched_cache_grp instead of p->mm->sched_cache_grp.\n\nKeep the fork/exec/exit reference management out of the generic mm\npaths: add sched_cache_fork(), sched_cache_fork_cleanup(),\nsched_cache_exec_mmap() and sched_cache_exit_mm() in\nkernel/sched/cache_sched.c (with empty stubs for !CONFIG_SCHED_CACHE),\nso fs/exec.c, kernel/fork.c and kernel/exit.c each call one helper\ninstead of open-coding the refcounting under #ifdef.  Also add\nsched_cache_group_get() and task_cache_group_get().","categories":["Operating systems"],"product":"Linux","vendor":"Linux","ecosystem":null,"affected_ranges":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-98866","source_modified_at":"2026-10-19T09:27:00.570Z","fetched_at":"2026-10-23T18:45:31.882637Z","product":"Linux","vendor":"Linux","versions":[{"version":"df0d98475954d655571979aa061ecb07d7e00392","lessThan":"9436130e6da72af63289a4acb3aa0c1df07a3928","status":"affected","versionType":"git"},{"version":"df0d98475954d655571979aa061ecb07d7e00392","lessThan":"b636fef85bda7d1bab9c0a45067ab1508d79d946","status":"affected","versionType":"git"}],"defaultStatus":"unaffected"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-98866","source_modified_at":"2026-10-19T09:27:00.570Z","fetched_at":"2026-10-23T18:45:31.882637Z","product":"Linux","vendor":"Linux","versions":[{"version":"7.2","status":"affected"},{"version":"0","lessThan":"7.2","status":"unaffected","versionType":"semver"},{"version":"7.2.10","lessThanOrEqual":"7.2.*","status":"unaffected","versionType":"semver"},{"version":"7.3","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}],"defaultStatus":"affected"}],"fixed_versions":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-98866","source_modified_at":"2026-10-19T09:27:00.570Z","fetched_at":"2026-10-23T18:45:31.882637Z","package":{"name":"Linux","ecosystem":null},"version":"9436130e6da72af63289a4acb3aa0c1df07a3928","basis":"first unaffected version stated in the CVE record"}],"cvss":null,"severity":null,"kev":{"listed":false},"epss":{"probability":0.00145,"percentile":0.03449,"score_date":"2026-10-23"},"published_at":"2026-10-18T15:51:27.883Z","modified_at":"2026-10-19T09:27:00.570Z","provenance":[{"source":"CVE List","url":"https://www.cve.org/CVERecord?id=CVE-2026-98866","fetched_at":"2026-10-23T18:45:31.882637Z","source_modified_at":"2026-10-19T09:27:00.570Z"},{"source":"EPSS","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-98866","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-23"}],"sources":["CVE List","EPSS"],"references":[{"source":"CVE List","url":"https://git.kernel.org/stable/c/9436130e6da72af63289a4acb3aa0c1df07a3928"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/b636fef85bda7d1bab9c0a45067ab1508d79d946"}],"locations":[],"motoko_assessment":{"status":"requires_architecture_review","automatic_remediation":false},"cve_state":"PUBLISHED","classification":{"method":"product-first software-layer rules","rules_version":"2.1","matched_on":"product","confidence":"heuristic","reviewed":false},"change_timestamp":"2026-10-19T09:27:00.570Z","content_hash":"bc58b8f0870e9911f1395bee050a6c76fd0ad90150aac7a850089db2d2e4f60e"}}