{
  "cveId": "CVE-2026-98861",
  "url": "https://patchblox.com/security/cve/CVE-2026-98861",
  "summary": "CVE-2026-98861 is fixed in linux on 1 platform by DEBIAN-CVE-2026-98861 (version 7.2.10-1), released October 19, 2026. It is not reported as exploited. Patch Radar priority: Routine.",
  "title": "linux: In the Linux kernel, the following vulnerability has been resolved:  fprobe: Use guard(rcu_sched_notrace) and check r...",
  "description": "In the Linux kernel, the following vulnerability has been resolved:  fprobe: Use guard(rcu_sched_notrace) and check rcu_is_watching()  unregister_fprobe() and unregister_fprobe_async() (used by BPF kprobe-multi) rely on standard RCU grace periods (synchronize_rcu() and call_rcu()) to wait until in-flight fprobe handlers complete before freeing the fprobe.  However, if an fprobe handler executes while RCU is not watching (such as in the idle loop or nohz_full extended quiescent states), standard RCU does not track preemption-disabled sections. Consequently, synchronize_rcu() does not wait for those executions, which can lead to a use-after-free if the fprobe is freed immediately after unregistration. Ensure handlers exit early when !rcu_is_watching().  Furthermore, fprobe_fgraph_entry() and fprobe_ftrace_entry() previously used guard(rcu)() and rcu_read_lock(), which invoke lockdep on every hit under CONFIG_PROVE_LOCKING. This adds overhead and can cause lockdep recursion if probed functions interact with lockdep.  Since rhltable_lookup() and rhl_for_each_entry_rcu() use rcu_dereference_all_check() (which checks rcu_read_lock_any_held()), holding preemption disabled via rcu_read_lock_sched_notrace() is fully valid and sufficient so long as rcu_is_watching() is true.  Define and use guard(rcu_sched_notrace)() across fprobe_ftrace_entry(), fprobe_fgraph_entry(), and fprobe_return(). This eliminates fast-path rcu_read_lock() and lockdep overhead while guaranteeing safe grace period synchronization.",
  "published": "2026-10-18T16:17:40Z",
  "severity": "",
  "epss": 0.00167,
  "epssPercentile": 0.05991,
  "priority": "Routine",
  "priorityTier": 4,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "fixes": [
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 14",
      "fixedVersion": "7.2.10-1",
      "fix": "DEBIAN-CVE-2026-98861",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-98861",
      "released": "2026-10-19T16:27:52Z"
    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-09T19:38:12Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}