CVE-2026-31774

Estado: AnalizadaAlta (7.1)—

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

io_uring/net: fix slab-out-of-bounds read in io_bundle_nbufs()

sqe->len is __u32 but gets stored into sr->len which is int. When userspace passes sqe->len values exceeding INT_MAX (e.g. 0xFFFFFFFF), sr->len overflows to a negative value. This negative value propagates through the bundle recv/send path:

This results in a slab-out-of-bounds read in io_bundle_nbufs() from the kmalloc-64 slab, as nbufs increments past the allocated iovec entries.

Fix this by rejecting negative sr->len values early in both io_sendmsg_prep() and io_recvmsg_prep(). Since sqe->len is __u32, any value > INT_MAX indicates overflow and is not a valid length.

Detalles técnicos trazas, registros y código del informe original

  1. io_recv(): sel.val = sr->len (ssize_t gets -1)
  2. io_recv_buf_select(): arg.max_len = sel->val (size_t gets
     0xFFFFFFFFFFFFFFFF)
  3. io_ring_buffers_peek(): buf->len is not clamped because max_len
     is astronomically large
  4. iov[].iov_len = 0xFFFFFFFF flows into io_bundle_nbufs()
  5. io_bundle_nbufs(): min_t(int, 0xFFFFFFFF, ret) yields -1,
     causing ret to increase instead of decrease, creating an
     infinite loop that reads past the allocated iov[] array

  BUG: KASAN: slab-out-of-bounds in io_bundle_nbufs+0x128/0x160
  Read of size 8 at addr ffff888100ae05c8 by task exp/145
  Call Trace:
   io_bundle_nbufs+0x128/0x160
   io_recv_finish+0x117/0xe20
   io_recv+0x2db/0x1160

CVSS

Versión: 3.1
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
Puntuación base: 7.1

Probabilidad de explotación (EPSS)

Probabilidad de explotación en los próximos 30 días: 0.17%
Percentil entre todas las CVEs puntuadas: 5
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 principalT1005 Data from Local Systemcollection80 %
Impacto secundarioT1499.004 Application or System Exploitationimpact75 %

Vulnerabilidad local de desbordamiento entero (CWE-125) en kernel Linux con AV:L/PR:L/UI:N. Permite lectura fuera de límites en slab memory (KASAN detectable) e infiniloop; sin ejecución de código remota.

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-125

Referencias

JSON original (NVD)

Mostrar

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      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nio_uring/net: fix slab-out-of-bounds read in io_bundle_nbufs()\n\nsqe->len is __u32 but gets stored into sr->len which is int. When\nuserspace passes sqe->len values exceeding INT_MAX (e.g. 0xFFFFFFFF),\nsr->len overflows to a negative value. This negative value propagates\nthrough the bundle recv/send path:\n\n  1. io_recv(): sel.val = sr->len (ssize_t gets -1)\n  2. io_recv_buf_select(): arg.max_len = sel->val (size_t gets\n     0xFFFFFFFFFFFFFFFF)\n  3. io_ring_buffers_peek(): buf->len is not clamped because max_len\n     is astronomically large\n  4. iov[].iov_len = 0xFFFFFFFF flows into io_bundle_nbufs()\n  5. io_bundle_nbufs(): min_t(int, 0xFFFFFFFF, ret) yields -1,\n     causing ret to increase instead of decrease, creating an\n     infinite loop that reads past the allocated iov[] array\n\nThis results in a slab-out-of-bounds read in io_bundle_nbufs() from\nthe kmalloc-64 slab, as nbufs increments past the allocated iovec\nentries.\n\n  BUG: KASAN: slab-out-of-bounds in io_bundle_nbufs+0x128/0x160\n  Read of size 8 at addr ffff888100ae05c8 by task exp/145\n  Call Trace:\n   io_bundle_nbufs+0x128/0x160\n   io_recv_finish+0x117/0xe20\n   io_recv+0x2db/0x1160\n\nFix this by rejecting negative sr->len values early in both\nio_sendmsg_prep() and io_recvmsg_prep(). Since sqe->len is __u32,\nany value > INT_MAX indicates overflow and is not a valid length."
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