{
  "cveId": "CVE-2026-98530",
  "url": "https://patchblox.com/security/cve/CVE-2026-98530",
  "summary": "CVE-2026-98530 is fixed in linux on 1 platform by DEBIAN-CVE-2026-98530 (version 7.2.9-1), 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:  kprobes: Fix permanent hang when flushing the kp...",
  "description": "In the Linux kernel, the following vulnerability has been resolved:  kprobes: Fix permanent hang when flushing the kprobe optimizer  Writing 0 to /proc/sys/debug/kprobes-optimization while a kprobe is jump-optimized never returns. The writer sleeps in D state forever with kprobe_sysctl_mutex held, so any later read or write of that sysctl hangs as well. For example, with vfs_read\u002B9 as an optimizable address in this build:    # cd /sys/kernel/tracing   # echo \u0027p:myprobe vfs_read\u002B9\u0027 \u003E\u003E kprobe_events   # echo 1 \u003E events/kprobes/myprobe/enable   # # wait until /sys/kernel/debug/kprobes/list shows [OPTIMIZED]   # echo 0 \u003E /proc/sys/debug/kprobes-optimization    INFO: task sh:246 blocked for more than 10 seconds.   Call Trace:    \u003CTASK\u003E    __schedule\u002B0x1176/0x4f70    schedule\u002B0xdc/0x2c0    schedule_timeout\u002B0x17b/0x260    wait_for_completion\u002B0x173/0x3c0    wait_for_kprobe_optimizer_locked\u002B0xbc/0x130    proc_kprobes_optimization_handler\u002B0x156/0x1b0    proc_sys_call_handler\u002B0x324/0x490    vfs_write\u002B0x52d/0xfe0    ksys_write\u002B0xff/0x200    do_syscall_64\u002B0x106/0x630    entry_SYSCALL_64_after_hwframe\u002B0x77/0x7f    \u003C/TASK\u003E   ...   INFO: task cat:265 is blocked on a mutex likely owned by task sh:246.  wait_for_kprobe_optimizer_locked() reinitializes optimizer_completion, asks the optimizer thread to flush and sleeps in wait_for_completion(). The thread drains the (un)optimizing lists, but calls complete() only if completion_done() is true, i.e. if the completion is already done, which never happens while someone waits. disarm_all_kprobes() and kprobe_trace_self_tests_init() wait the same way.  Calling complete() unconditionally would not be enough: the waiter drops kprobe_mutex while it sleeps, and nothing else serializes the sysctl handler against the debugfs \u0022enabled\u0022 file. A second flusher that still finds the lists non-empty, e.g. because a disabled probe is queued for unoptimizing, reinitializes the completion under the first:    sysctl write                      debugfs \u0022enabled\u0022 write   unoptimize_all_kprobes()     wait_for_kprobe_optimizer_locked()       init_completion(c)       mutex_unlock(\u0026kprobe_mutex)       wait_for_completion(c)                                     disarm_all_kprobes()                                       wait_for_kprobe_optimizer_locked()                                         init_completion(c)                                           // c-\u003Ewait is reset, the first                                           // waiter is off the queue                                         mutex_unlock(\u0026kprobe_mutex)                                         wait_for_completion(c)   kprobe_optimizer()     complete(c)       // wakes the debugfs writer only  where c is \u0026optimizer_completion. Lining up the two writes during an optimizer pass loses the sysctl writer this way.  Replace the completion with a counter of optimizer passes, bumped at the end of each pass and signalled with wake_up_var_locked(), both under kprobe_mutex. A flusher samples the count and waits with wait_var_event_mutex(), which drops kprobe_mutex only while sleeping, so a new count means a whole pass ran in the meantime. Nothing is reinitialized, so several flushers can sleep in the wait at once.",
  "published": "2026-10-18T16:17:04Z",
  "severity": "",
  "epss": 0.00198,
  "epssPercentile": 0.09617,
  "priority": "Routine",
  "priorityTier": 4,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "fixes": [
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 14",
      "fixedVersion": "7.2.9-1",
      "fix": "DEBIAN-CVE-2026-98530",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-98530",
      "released": "2026-10-19T16:27:52Z"
    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-09T13:31:49Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}