CVE-2026-23192

Estado: ModificadaAlta (7.8)—

In the Linux kernel, the following vulnerability has been resolved:

linkwatch: use __dev_put() in callers to prevent UAF

After linkwatch_do_dev() calls __dev_put() to release the linkwatch reference, the device refcount may drop to 1. At this point, netdev_run_todo() can proceed (since linkwatch_sync_dev() sees an empty list and returns without blocking), wait for the refcount to become 1 via netdev_wait_allrefs_any(), and then free the device via kobject_put().

This creates a use-after-free when __linkwatch_run_queue() tries to call netdev_unlock_ops() on the already-freed device.

Note that adding netdev_lock_ops()/netdev_unlock_ops() pair in netdev_run_todo() before kobject_put() would not work, because netdev_lock_ops() is conditional - it only locks when netdev_need_ops_lock() returns true.

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If the device doesn't require ops_lock, linkwatch won't hold any lock, and netdev_run_todo() acquiring the lock won't provide synchronization.

Fix this by moving __dev_put() from linkwatch_do_dev() to its callers. The device reference logically pairs with de-listing the device, so it's reasonable for the caller that did the de-listing to release it. This allows placing __dev_put() after all device accesses are complete, preventing UAF.

The bug can be reproduced by adding mdelay(2000) after linkwatch_do_dev() in __linkwatch_run_queue(), then running:

Detalles técnicos trazas, registros y código del informe original

  ip tuntap add mode tun name tun_test
  ip link set tun_test up
  ip link set tun_test carrier off
  ip link set tun_test carrier on
  sleep 0.5
  ip tuntap del mode tun name tun_test

KASAN report:

 ==================================================================
 BUG: KASAN: use-after-free in netdev_need_ops_lock include/net/netdev_lock.h:33 [inline]
 BUG: KASAN: use-after-free in netdev_unlock_ops include/net/netdev_lock.h:47 [inline]
 BUG: KASAN: use-after-free in __linkwatch_run_queue+0x865/0x8a0 net/core/link_watch.c:245
 Read of size 8 at addr ffff88804de5c008 by task kworker/u32:10/8123

 CPU: 0 UID: 0 PID: 8123 Comm: kworker/u32:10 Not tainted syzkaller #0 PREEMPT(full)
 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
 Workqueue: events_unbound linkwatch_event
 Call Trace:
  <TASK>
  __dump_stack lib/dump_stack.c:94 [inline]
  dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
  print_address_description mm/kasan/report.c:378 [inline]
  print_report+0x156/0x4c9 mm/kasan/report.c:482
  kasan_report+0xdf/0x1a0 mm/kasan/report.c:595
  netdev_need_ops_lock include/net/netdev_lock.h:33 [inline]
  netdev_unlock_ops include/net/netdev_lock.h:47 [inline]
  __linkwatch_run_queue+0x865/0x8a0 net/core/link_watch.c:245
  linkwatch_event+0x8f/0xc0 net/core/link_watch.c:304
  process_one_work+0x9c2/0x1840 kernel/workqueue.c:3257
  process_scheduled_works kernel/workqueue.c:3340 [inline]
  worker_thread+0x5da/0xe40 kernel/workqueue.c:3421
  kthread+0x3b3/0x730 kernel/kthread.c:463
  ret_from_fork+0x754/0xaf0 arch/x86/kernel/process.c:158
  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
  </TASK>
 ==================================================================

CVSS

Versión: 3.1
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Puntuación base: 7.8

Probabilidad de explotación (EPSS)

Probabilidad de explotación en los próximos 30 días: 0.13%
Percentil entre todas las CVEs puntuadas: 2
Fecha de la puntuación: 6/10/2026

EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).

🎯 Técnicas ATT&CK

Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.

ExplotaciónT1068 Exploitation for Privilege Escalationprivilege escalation85 %
Impacto principalT1499.004 Application or System Exploitationimpact75 %
Impacto secundarioT1529 System Shutdown/Rebootimpact65 %

Vulnerabilidad UAF en kernel Linux con acceso local (AV:L, PR:L) sin interacción. El impacto es DoS por crash (KASAN) y potencial ejecución arbitraria al corromper memoria del kernel.

Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.

🛡️ Mitigaciones ATT&CK que cubren estas técnicas

Threat Intelligence Program Filter Network Traffic Execution Prevention Application Isolation and Sandboxing Exploit Protection Update Software

Tecnologías afectadas (1)

Linux — Linux Kernel

CWE

CWE-416

Referencias

JSON original (NVD)

Mostrar

{
  "id": "CVE-2026-23192",
  "cveTags": [],
  "metrics": {
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 7.8,
          "attackVector": "LOCAL",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "confidentialityImpact": "HIGH"
        },
        "impactScore": 5.9,
        "exploitabilityScore": 1.8
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        "source": "nvd@nist.gov",
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          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "confidentialityImpact": "HIGH"
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        "impactScore": 5.9,
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      "affectedData": [
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          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
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              "status": "affected",
              "version": "04efcee6ef8d0f01eef495db047e7216d6e6e38f",
              "lessThan": "2718ae6af7445ba2ee0abf6365ca43a9a3b16aeb",
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          ],
          "programFiles": [
            "net/core/link_watch.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.15"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "6.15",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "6.18.10",
              "versionType": "semver",
              "lessThanOrEqual": "6.18.*"
            },
            {
              "status": "unaffected",
              "version": "6.19",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
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          ],
          "programFiles": [
            "net/core/link_watch.c"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2026-02-14T17:15:57.020",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/2718ae6af7445ba2ee0abf6365ca43a9a3b16aeb",
      "tags": [
        "Patch"
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      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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      "tags": [
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      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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  ],
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "type": "Primary",
      "source": "nvd@nist.gov",
      "description": [
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          "lang": "en",
          "value": "CWE-416"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nlinkwatch: use __dev_put() in callers to prevent UAF\n\nAfter linkwatch_do_dev() calls __dev_put() to release the linkwatch\nreference, the device refcount may drop to 1. At this point,\nnetdev_run_todo() can proceed (since linkwatch_sync_dev() sees an\nempty list and returns without blocking), wait for the refcount to\nbecome 1 via netdev_wait_allrefs_any(), and then free the device\nvia kobject_put().\n\nThis creates a use-after-free when __linkwatch_run_queue() tries to\ncall netdev_unlock_ops() on the already-freed device.\n\nNote that adding netdev_lock_ops()/netdev_unlock_ops() pair in\nnetdev_run_todo() before kobject_put() would not work, because\nnetdev_lock_ops() is conditional - it only locks when\nnetdev_need_ops_lock() returns true. If the device doesn't require\nops_lock, linkwatch won't hold any lock, and netdev_run_todo()\nacquiring the lock won't provide synchronization.\n\nFix this by moving __dev_put() from linkwatch_do_dev() to its\ncallers. The device reference logically pairs with de-listing the\ndevice, so it's reasonable for the caller that did the de-listing\nto release it. This allows placing __dev_put() after all device\naccesses are complete, preventing UAF.\n\nThe bug can be reproduced by adding mdelay(2000) after\nlinkwatch_do_dev() in __linkwatch_run_queue(), then running:\n\n  ip tuntap add mode tun name tun_test\n  ip link set tun_test up\n  ip link set tun_test carrier off\n  ip link set tun_test carrier on\n  sleep 0.5\n  ip tuntap del mode tun name tun_test\n\nKASAN report:\n\n ==================================================================\n BUG: KASAN: use-after-free in netdev_need_ops_lock include/net/netdev_lock.h:33 [inline]\n BUG: KASAN: use-after-free in netdev_unlock_ops include/net/netdev_lock.h:47 [inline]\n BUG: KASAN: use-after-free in __linkwatch_run_queue+0x865/0x8a0 net/core/link_watch.c:245\n Read of size 8 at addr ffff88804de5c008 by task kworker/u32:10/8123\n\n CPU: 0 UID: 0 PID: 8123 Comm: kworker/u32:10 Not tainted syzkaller #0 PREEMPT(full)\n Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014\n Workqueue: events_unbound linkwatch_event\n Call Trace:\n  <TASK>\n  __dump_stack lib/dump_stack.c:94 [inline]\n  dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120\n  print_address_description mm/kasan/report.c:378 [inline]\n  print_report+0x156/0x4c9 mm/kasan/report.c:482\n  kasan_report+0xdf/0x1a0 mm/kasan/report.c:595\n  netdev_need_ops_lock include/net/netdev_lock.h:33 [inline]\n  netdev_unlock_ops include/net/netdev_lock.h:47 [inline]\n  __linkwatch_run_queue+0x865/0x8a0 net/core/link_watch.c:245\n  linkwatch_event+0x8f/0xc0 net/core/link_watch.c:304\n  process_one_work+0x9c2/0x1840 kernel/workqueue.c:3257\n  process_scheduled_works kernel/workqueue.c:3340 [inline]\n  worker_thread+0x5da/0xe40 kernel/workqueue.c:3421\n  kthread+0x3b3/0x730 kernel/kthread.c:463\n  ret_from_fork+0x754/0xaf0 arch/x86/kernel/process.c:158\n  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246\n  </TASK>\n =================================================================="
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nlinkwatch: usar __dev_put() en las funciones que llaman para prevenir UAF\n\nDespués de que linkwatch_do_dev() llama a __dev_put() para liberar la referencia de linkwatch, el contador de referencias del dispositivo puede bajar a 1. En este punto, netdev_run_todo() puede continuar (ya que linkwatch_sync_dev() ve una lista vacía y regresa sin bloquear), esperar a que el contador de referencias llegue a 1 a través de netdev_wait_allrefs_any(), y luego liberar el dispositivo a través de kobject_put().\n\nEsto crea un uso después de liberación cuando __linkwatch_run_queue() intenta llamar a netdev_unlock_ops() en el dispositivo ya liberado.\n\nTenga en cuenta que añadir el par netdev_lock_ops()/netdev_unlock_ops() en netdev_run_todo() antes de kobject_put() no funcionaría, porque netdev_lock_ops() es condicional - solo bloquea cuando netdev_need_ops_lock() devuelve verdadero. Si el dispositivo no requiere ops_lock, linkwatch no mantendrá ningún bloqueo, y netdev_run_todo() al adquirir el bloqueo no proporcionará sincronización.\n\nSolucione esto moviendo __dev_put() de linkwatch_do_dev() a sus funciones que llaman. La referencia del dispositivo se empareja lógicamente con la eliminación del dispositivo de la lista, por lo que es razonable que la función que realizó la eliminación de la lista lo libere. Esto permite colocar __dev_put() después de que todos los accesos al dispositivo estén completos, previniendo UAF.\n\nEl error puede reproducirse añadiendo mdelay(2000) después de linkwatch_do_dev() en __linkwatch_run_queue(), luego ejecutando:\n\n  ip tuntap add mode tun name tun_test\n  ip link set tun_test up\n  ip link set tun_test carrier off\n  ip link set tun_test carrier on\n  sleep 0.5\n  ip tuntap del mode tun name tun_test\n\nInforme KASAN:\n\n ==================================================================\n BUG: KASAN: uso después de liberación in netdev_need_ops_lock include/net/netdev_lock.h:33 [inline]\n BUG: KASAN: uso después de liberación in netdev_unlock_ops include/net/netdev_lock.h:47 [inline]\n BUG: KASAN: uso después de liberación in __linkwatch_run_queue+0x865/0x8a0 net/core/link_watch.c:245\n Read of size 8 at addr ffff88804de5c008 by task kworker/u32:10/8123\n\n CPU: 0 UID: 0 PID: 8123 Comm: kworker/u32:10 Not tainted syzkaller #0 PREEMPT(full)\n Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014\n Workqueue: events_unbound linkwatch_event\n Call Trace:\n  \n  __dump_stack lib/dump_stack.c:94 [inline]\n  dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120\n  print_address_description mm/kasan/report.c:378 [inline]\n  print_report+0x156/0x4c9 mm/kasan/report.c:482\n  kasan_report+0xdf/0x1a0 mm/kasan/report.c:595\n  netdev_need_ops_lock include/net/netdev_lock.h:33 [inline]\n  netdev_unlock_ops include/net/netdev_lock.h:47 [inline]\n  __linkwatch_run_queue+0x865/0x8a0 net/core/link_watch.c:245\n  linkwatch_event+0x8f/0xc0 net/core/link_watch.c:304\n  process_one_work+0x9c2/0x1840 kernel/workqueue.c:3257\n  process_scheduled_works kernel/workqueue.c:3340 [inline]\n  worker_thread+0x5da/0xe40 kernel/workqueue.c:3421\n  kthread+0x3b3/0x730 kernel/kthread.c:463\n  ret_from_fork+0x754/0xaf0 arch/x86/kernel/process.c:158\n  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246\n  \n =================================================================="
    }
  ],
  "lastModified": "2026-06-17T10:21:04.267",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
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}