{
  "cveId": "CVE-2021-47089",
  "url": "https://patchblox.com/security/cve/CVE-2021-47089",
  "summary": "CVE-2021-47089 is fixed in linux on 1 platform, first by DEBIAN-CVE-2021-47089, released March 4, 2024. It is not reported as exploited. Patch Radar priority: Routine.",
  "title": "linux: In the Linux kernel, the following vulnerability has been resolved:  kfence: fix memory leak when cat kfence objects...",
  "description": "In the Linux kernel, the following vulnerability has been resolved:  kfence: fix memory leak when cat kfence objects  Hulk robot reported a kmemleak problem:      unreferenced object 0xffff93d1d8cc02e8 (size 248):       comm \u0022cat\u0022, pid 23327, jiffies 4624670141 (age 495992.217s)       hex dump (first 32 bytes):         00 40 85 19 d4 93 ff ff 00 10 00 00 00 00 00 00  .@..............         00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................       backtrace:          seq_open\u002B0x2a/0x80          full_proxy_open\u002B0x167/0x1e0          do_dentry_open\u002B0x1e1/0x3a0          path_openat\u002B0x961/0xa20          do_filp_open\u002B0xae/0x120          do_sys_openat2\u002B0x216/0x2f0          do_sys_open\u002B0x57/0x80          do_syscall_64\u002B0x33/0x40          entry_SYSCALL_64_after_hwframe\u002B0x44/0xa9     unreferenced object 0xffff93d419854000 (size 4096):       comm \u0022cat\u0022, pid 23327, jiffies 4624670141 (age 495992.217s)       hex dump (first 32 bytes):         6b 66 65 6e 63 65 2d 23 32 35 30 3a 20 30 78 30  kfence-#250: 0x0         30 30 30 30 30 30 30 37 35 34 62 64 61 31 32 2d  0000000754bda12-       backtrace:          seq_read_iter\u002B0x313/0x440          seq_read\u002B0x14b/0x1a0          full_proxy_read\u002B0x56/0x80          vfs_read\u002B0xa5/0x1b0          ksys_read\u002B0xa0/0xf0          do_syscall_64\u002B0x33/0x40          entry_SYSCALL_64_after_hwframe\u002B0x44/0xa9  I find that we can easily reproduce this problem with the following commands:  \tcat /sys/kernel/debug/kfence/objects \techo scan \u003E /sys/kernel/debug/kmemleak \tcat /sys/kernel/debug/kmemleak  The leaked memory is allocated in the stack below:      do_syscall_64       do_sys_open         do_dentry_open           full_proxy_open             seq_open            ---\u003E alloc seq_file       vfs_read         full_proxy_read           seq_read             seq_read_iter               traverse          ---\u003E alloc seq_buf  And it should have been released in the following process:      do_syscall_64       syscall_exit_to_user_mode         exit_to_user_mode_prepare           task_work_run             ____fput               __fput                 full_proxy_release  ---\u003E free here  However, the release function corresponding to file_operations is not implemented in kfence.  As a result, a memory leak occurs.  Therefore, the solution to this problem is to implement the corresponding release function.",
  "published": "2024-03-04T18:15:07Z",
  "severity": "low",
  "cvss": 3.3,
  "cvssVector": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L",
  "epss": 0.0019,
  "epssPercentile": 0.08705,
  "priority": "Routine",
  "priorityTier": 4,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "fixes": [
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 12.15 (bookworm)",
      "fixedVersion": "5.15.15-1",
      "fix": "DEBIAN-CVE-2021-47089",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2021-47089",
      "released": "2024-03-04T18:15:07Z"
    },
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 13.5 (trixie)",
      "fixedVersion": "5.15.15-1",
      "fix": "DEBIAN-CVE-2021-47089",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2021-47089",
      "released": "2024-03-04T18:15:07Z"
    },
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 14",
      "fixedVersion": "5.15.15-1",
      "fix": "DEBIAN-CVE-2021-47089",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2021-47089",
      "released": "2024-03-04T18:15:07Z"
    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-08T13:06:02Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}