{
  "cveId": "CVE-2026-64451",
  "url": "https://patchblox.com/security/cve/CVE-2026-64451",
  "summary": "CVE-2026-64451 is fixed in linux on 1 platform by DEBIAN-CVE-2026-64451 (version 7.1.4-1), released August 7, 2026. It is not reported as exploited. Patch Radar priority: Routine.",
  "title": "linux: In the Linux kernel, the following vulnerability has been resolved:  tracing: Fix NULL pointer dereference in func_se...",
  "description": "In the Linux kernel, the following vulnerability has been resolved:  tracing: Fix NULL pointer dereference in func_set_flag()  func_set_flag() dereferences tr-\u003Ecurrent_trace_flags before verifying that the current tracer is actually the function tracer. When the active tracer has been switched away from \u0022function\u0022 (e.g., to \u0022wakeup_rt\u0022), tr-\u003Ecurrent_trace_flags can be NULL, leading to a NULL pointer dereference and kernel crash.  The call chain that triggers this is:    trace_options_write()     -\u003E __set_tracer_option()       -\u003E trace-\u003Eset_flag()          /* func_set_flag */  In func_set_flag(), the first operation is:    if (!!set == !!(tr-\u003Ecurrent_trace_flags-\u003Eval \u0026 bit))  This dereferences tr-\u003Ecurrent_trace_flags unconditionally. The safety check that guards against a non-function tracer:    if (tr-\u003Ecurrent_trace != \u0026function_trace)       return 0;  is placed *after* the dereference, which is too late.  This was observed with the following crash dump:    BUG: unable to handle page fault at 0000000000000000   RIP: func_set_flag\u002B0xd    Call Trace:    __set_tracer_option\u002B0x27    trace_options_write\u002B0x75    vfs_write\u002B0x12a    ksys_write\u002B0x66    do_syscall_64\u002B0x5b    RIP: ffffffff914c973d  RSP: ff67ec88b01dfdf0  RFLAGS: 00010202   RAX: 0000000000000000  RBX: ff3a826e80354580  RCX: 0000000000000001   RDX: 0000000000000001  RSI: 0000000000000000  RDI: ffffffff93918080  The disassembly confirms the fault:    func_set_flag\u002B0:   mov 0x1f08(%rdi), %rax  ; RAX = tr-\u003Ecurrent_trace_flags = NULL   func_set_flag\u002B13:  mov (%rax), %eax        ; page fault: dereference NULL  At the time of the crash:   tr-\u003Ecurrent_trace_flags = 0x0 (NULL)   tr-\u003Ecurrent_trace = wakeup_rt_tracer (not function_trace)  The scenario is that a process opens a function tracer option file (such as \u0022func_stack_trace\u0022), then the current tracer is switched to another tracer (e.g., \u0022wakeup_rt\u0022), which sets current_trace_flags to NULL. When the process subsequently writes to the option file, func_set_flag() is invoked and crashes on the NULL dereference.  Fix this by moving the current_trace check before the current_trace_flags dereference, so that func_set_flag() returns early when the function tracer is not active.",
  "published": "2026-07-25T10:17:30Z",
  "severity": "medium",
  "cvss": 5.5,
  "cvssVector": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
  "epss": 0.00143,
  "epssPercentile": 0.03659,
  "priority": "Routine",
  "priorityTier": 4,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "fixes": [
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 14",
      "fixedVersion": "7.1.4-1",
      "fix": "DEBIAN-CVE-2026-64451",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-64451",
      "released": "2026-08-07T15:22:10Z"
    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-08T00:53:09Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}