CVE-2026-74289

Estado: RecibidaAlta (7.8)—

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

ipv4: fib: Don't dump dying fib_info in fib_leaf_notify().

syzbot reported use-after-free in nsim_fib4_prepare_event(). [0]

The problem is that the following functions call fib_info_hold() / refcount_inc() while dumping fib_info under RCU, which is unsafe.

refcount_inc_not_zero() must be used, but it would be too late there.

Let's guarantee the lifetime of fib_info in fib_leaf_notify().

Note that IPv6 does not need the corresponding change since fib6_table_dump() holds fib6_table.tb6_lock.

Detalles técnicos trazas, registros y código del informe original

  * mlxsw_sp_router_fib4_event()
  * rocker_router_fib_event()
  * nsim_fib4_prepare_event()

[0]:
refcount_t: addition on 0; use-after-free.
WARNING: lib/refcount.c:25 at refcount_warn_saturate+0x9f/0x110 lib/refcount.c:25, CPU#0: kworker/u8:15/3420
Modules linked in:
CPU: 0 UID: 0 PID: 3420 Comm: kworker/u8:15 Not tainted syzkaller #0 PREEMPT_{RT,(full)}
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Workqueue: netns cleanup_net
RIP: 0010:refcount_warn_saturate+0x9f/0x110 lib/refcount.c:25
Code: eb 66 85 db 74 3e 83 fb 01 75 4c e8 1b f1 22 fd 48 8d 3d 84 cb f1 0a 67 48 0f b9 3a eb 4a e8 08 f1 22 fd 48 8d 3d 81 cb f1 0a <67> 48 0f b9 3a eb 37 e8 f5 f0 22 fd 48 8d 3d 7e cb f1 0a 67 48 0f
RSP: 0018:ffffc9000f2c7270 EFLAGS: 00010293
RAX: ffffffff84a18858 RBX: 0000000000000002 RCX: ffff888032ff9ec0
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8f9353e0
RBP: 0000000000000000 R08: ffff888032ff9ec0 R09: 0000000000000005
R10: 0000000000000100 R11: 0000000000000004 R12: ffff8880570cc000
R13: dffffc0000000000 R14: ffff88802b40563c R15: ffff8880570cc000
FS:  0000000000000000(0000) GS:ffff888126173000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb1f4d5d000 CR3: 000000006072a000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 __refcount_add include/linux/refcount.h:-1 [inline]
 __refcount_inc include/linux/refcount.h:366 [inline]
 refcount_inc include/linux/refcount.h:383 [inline]
 fib_info_hold include/net/ip_fib.h:629 [inline]
 nsim_fib4_prepare_event drivers/net/netdevsim/fib.c:930 [inline]
 nsim_fib_event_schedule_work drivers/net/netdevsim/fib.c:1000 [inline]
 nsim_fib_event_nb+0x1055/0x1240 drivers/net/netdevsim/fib.c:1043
 call_fib_notifier+0x45/0x80 net/core/fib_notifier.c:25
 call_fib_entry_notifier net/ipv4/fib_trie.c:90 [inline]
 fib_leaf_notify net/ipv4/fib_trie.c:2176 [inline]
 fib_table_notify net/ipv4/fib_trie.c:2194 [inline]
 fib_notify+0x36b/0x5e0 net/ipv4/fib_trie.c:2217
 fib_net_dump net/core/fib_notifier.c:70 [inline]
 register_fib_notifier+0x184/0x360 net/core/fib_notifier.c:108
 nsim_fib_create+0x85d/0x9f0 drivers/net/netdevsim/fib.c:1596
 nsim_dev_reload_create drivers/net/netdevsim/dev.c:1604 [inline]
 nsim_dev_reload_up+0x374/0x7c0 drivers/net/netdevsim/dev.c:1058
 devlink_reload+0x501/0x8d0 net/devlink/dev.c:475
 devlink_pernet_pre_exit+0x1ff/0x420 net/devlink/core.c:558
 ops_pre_exit_list net/core/net_namespace.c:161 [inline]
 ops_undo_list+0x187/0x940 net/core/net_namespace.c:234
 cleanup_net+0x56e/0x800 net/core/net_namespace.c:702
 process_one_work kernel/workqueue.c:3314 [inline]
 process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3397
 worker_thread+0xa53/0xfc0 kernel/workqueue.c:3478
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </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 escalation75 %
Impacto principalT1499.004 Application or System Exploitationimpact65 %
Impacto secundarioT1529 System Shutdown/Rebootimpact60 %

Vulnerabilidad de use-after-free en kernel Linux con acceso local (AV:L, PR:L) sin interacción. Permite denial of service o corrupción de memoria; impacto alto en C/I/A.

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)

⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.

Linux — Linux Kernel^AI

Referencias

JSON original (NVD)

Mostrar

{
  "id": "CVE-2026-74289",
  "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
      }
    ]
  },
  "affected": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "affectedData": [
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "c3852ef7f2f8f75a9f85a864bec1f6f5a3068eea",
              "lessThan": "8bdb20b8a581495062b5879f4e9d435da648b3b0",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "c3852ef7f2f8f75a9f85a864bec1f6f5a3068eea",
              "lessThan": "7907a395701b339c2d68f37456d395e953c74795",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "c3852ef7f2f8f75a9f85a864bec1f6f5a3068eea",
              "lessThan": "7980a13add57f97c5da1dc961d0145a6ad2a7f98",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "c3852ef7f2f8f75a9f85a864bec1f6f5a3068eea",
              "lessThan": "bea03e887db5a8a79234531faf14cf2c4d8816c3",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "c3852ef7f2f8f75a9f85a864bec1f6f5a3068eea",
              "lessThan": "676482da8d938ea72c26da0fc86af2d2ec238ab2",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "c3852ef7f2f8f75a9f85a864bec1f6f5a3068eea",
              "lessThan": "06b693d2eb6651a63ad85bad8673de3b7d4edd6d",
              "versionType": "git"
            }
          ],
          "programFiles": [
            "include/net/ip_fib.h",
            "net/ipv4/fib_trie.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "4.10"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "4.10",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "6.1.189",
              "versionType": "semver",
              "lessThanOrEqual": "6.1.*"
            },
            {
              "status": "unaffected",
              "version": "6.6.158",
              "versionType": "semver",
              "lessThanOrEqual": "6.6.*"
            },
            {
              "status": "unaffected",
              "version": "6.12.111",
              "versionType": "semver",
              "lessThanOrEqual": "6.12.*"
            },
            {
              "status": "unaffected",
              "version": "6.18.53",
              "versionType": "semver",
              "lessThanOrEqual": "6.18.*"
            },
            {
              "status": "unaffected",
              "version": "7.1.5",
              "versionType": "semver",
              "lessThanOrEqual": "7.1.*"
            },
            {
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "include/net/ip_fib.h",
            "net/ipv4/fib_trie.c"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2026-08-15T06:22:28.457",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/06b693d2eb6651a63ad85bad8673de3b7d4edd6d",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/676482da8d938ea72c26da0fc86af2d2ec238ab2",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/7907a395701b339c2d68f37456d395e953c74795",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/7980a13add57f97c5da1dc961d0145a6ad2a7f98",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/8bdb20b8a581495062b5879f4e9d435da648b3b0",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/bea03e887db5a8a79234531faf14cf2c4d8816c3",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Received",
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nipv4: fib: Don't dump dying fib_info in fib_leaf_notify().\n\nsyzbot reported use-after-free in nsim_fib4_prepare_event(). [0]\n\nThe problem is that the following functions call fib_info_hold() /\nrefcount_inc() while dumping fib_info under RCU, which is unsafe.\n\n  * mlxsw_sp_router_fib4_event()\n  * rocker_router_fib_event()\n  * nsim_fib4_prepare_event()\n\nrefcount_inc_not_zero() must be used, but it would be too late\nthere.\n\nLet's guarantee the lifetime of fib_info in fib_leaf_notify().\n\nNote that IPv6 does not need the corresponding change since\nfib6_table_dump() holds fib6_table.tb6_lock.\n\n[0]:\nrefcount_t: addition on 0; use-after-free.\nWARNING: lib/refcount.c:25 at refcount_warn_saturate+0x9f/0x110 lib/refcount.c:25, CPU#0: kworker/u8:15/3420\nModules linked in:\nCPU: 0 UID: 0 PID: 3420 Comm: kworker/u8:15 Not tainted syzkaller #0 PREEMPT_{RT,(full)}\nHardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026\nWorkqueue: netns cleanup_net\nRIP: 0010:refcount_warn_saturate+0x9f/0x110 lib/refcount.c:25\nCode: eb 66 85 db 74 3e 83 fb 01 75 4c e8 1b f1 22 fd 48 8d 3d 84 cb f1 0a 67 48 0f b9 3a eb 4a e8 08 f1 22 fd 48 8d 3d 81 cb f1 0a <67> 48 0f b9 3a eb 37 e8 f5 f0 22 fd 48 8d 3d 7e cb f1 0a 67 48 0f\nRSP: 0018:ffffc9000f2c7270 EFLAGS: 00010293\nRAX: ffffffff84a18858 RBX: 0000000000000002 RCX: ffff888032ff9ec0\nRDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8f9353e0\nRBP: 0000000000000000 R08: ffff888032ff9ec0 R09: 0000000000000005\nR10: 0000000000000100 R11: 0000000000000004 R12: ffff8880570cc000\nR13: dffffc0000000000 R14: ffff88802b40563c R15: ffff8880570cc000\nFS:  0000000000000000(0000) GS:ffff888126173000(0000) knlGS:0000000000000000\nCS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\nCR2: 00007fb1f4d5d000 CR3: 000000006072a000 CR4: 00000000003526f0\nCall Trace:\n <TASK>\n __refcount_add include/linux/refcount.h:-1 [inline]\n __refcount_inc include/linux/refcount.h:366 [inline]\n refcount_inc include/linux/refcount.h:383 [inline]\n fib_info_hold include/net/ip_fib.h:629 [inline]\n nsim_fib4_prepare_event drivers/net/netdevsim/fib.c:930 [inline]\n nsim_fib_event_schedule_work drivers/net/netdevsim/fib.c:1000 [inline]\n nsim_fib_event_nb+0x1055/0x1240 drivers/net/netdevsim/fib.c:1043\n call_fib_notifier+0x45/0x80 net/core/fib_notifier.c:25\n call_fib_entry_notifier net/ipv4/fib_trie.c:90 [inline]\n fib_leaf_notify net/ipv4/fib_trie.c:2176 [inline]\n fib_table_notify net/ipv4/fib_trie.c:2194 [inline]\n fib_notify+0x36b/0x5e0 net/ipv4/fib_trie.c:2217\n fib_net_dump net/core/fib_notifier.c:70 [inline]\n register_fib_notifier+0x184/0x360 net/core/fib_notifier.c:108\n nsim_fib_create+0x85d/0x9f0 drivers/net/netdevsim/fib.c:1596\n nsim_dev_reload_create drivers/net/netdevsim/dev.c:1604 [inline]\n nsim_dev_reload_up+0x374/0x7c0 drivers/net/netdevsim/dev.c:1058\n devlink_reload+0x501/0x8d0 net/devlink/dev.c:475\n devlink_pernet_pre_exit+0x1ff/0x420 net/devlink/core.c:558\n ops_pre_exit_list net/core/net_namespace.c:161 [inline]\n ops_undo_list+0x187/0x940 net/core/net_namespace.c:234\n cleanup_net+0x56e/0x800 net/core/net_namespace.c:702\n process_one_work kernel/workqueue.c:3314 [inline]\n process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3397\n worker_thread+0xa53/0xfc0 kernel/workqueue.c:3478\n kthread+0x388/0x470 kernel/kthread.c:436\n ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158\n ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245\n </TASK>"
    }
  ],
  "lastModified": "2026-10-03T11:17:38.280",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}