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CVE-2026-64417

Estado: AnalizadaMedia (5.5)—

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

mm: shrinker: fix NULL pointer dereference in debugfs

shrinker_debugfs_add() creates both "count" and "scan" debugfs files unconditionally.

That assumes every shrinker implements both count_objects() and scan_objects(), which is not guaranteed. For example, the xen-backend shrinker sets count_objects() but leaves scan_objects() NULL, so writing to its scan file calls through a NULL function pointer and panics the kernel:

The count path has the same issue in principle if a shrinker omits count_objects().

To fix it, only create "count" and "scan" debugfs files when the corresponding callbacks are present.

Detalles técnicos trazas, registros y código del informe original
BUG: kernel NULL pointer dereference, address: 0000000000000000
RIP: 0010:0x0
Code: Unable to access opcode bytes at 0xffffffffffffffd6.
Call Trace:
 <TASK>
 shrinker_debugfs_scan_write+0x12e/0x270
 full_proxy_write+0x5f/0x90
 vfs_write+0xde/0x420
 ? filp_flush+0x75/0x90
 ? filp_close+0x1d/0x30
 ? do_dup2+0xb8/0x120
 ksys_write+0x68/0xf0
 ? filp_flush+0x75/0x90
 do_syscall_64+0xb3/0x5b0
 entry_SYSCALL_64_after_hwframe+0x76/0x7e

CVSS

Probabilidad de explotación (EPSS)

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).

Tecnologías afectadas (1)

Linux — Linux Kernel

CWE

Referencias

JSON original (NVD)

Mostrar
{
  "id": "CVE-2026-64417",
  "cveTags": [],
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        "source": "nvd@nist.gov",
        "cvssData": {
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          "version": "3.1",
          "baseScore": 5.5,
          "attackVector": "LOCAL",
          "baseSeverity": "MEDIUM",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
          "integrityImpact": "NONE",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "confidentialityImpact": "NONE"
        },
        "impactScore": 3.6,
        "exploitabilityScore": 1.8
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  "published": "2026-07-25T10:17:25.567",
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  "vulnStatus": "Analyzed",
  "weaknesses": [
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      "type": "Primary",
      "source": "nvd@nist.gov",
      "description": [
        {
          "lang": "en",
          "value": "CWE-476"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm: shrinker: fix NULL pointer dereference in debugfs\n\nshrinker_debugfs_add() creates both \"count\" and \"scan\" debugfs files\nunconditionally.\n\nThat assumes every shrinker implements both count_objects() and\nscan_objects(), which is not guaranteed.  For example, the xen-backend\nshrinker sets count_objects() but leaves scan_objects() NULL, so writing\nto its scan file calls through a NULL function pointer and panics the\nkernel:\n\nBUG: kernel NULL pointer dereference, address: 0000000000000000\nRIP: 0010:0x0\nCode: Unable to access opcode bytes at 0xffffffffffffffd6.\nCall Trace:\n <TASK>\n shrinker_debugfs_scan_write+0x12e/0x270\n full_proxy_write+0x5f/0x90\n vfs_write+0xde/0x420\n ? filp_flush+0x75/0x90\n ? filp_close+0x1d/0x30\n ? do_dup2+0xb8/0x120\n ksys_write+0x68/0xf0\n ? filp_flush+0x75/0x90\n do_syscall_64+0xb3/0x5b0\n entry_SYSCALL_64_after_hwframe+0x76/0x7e\n\nThe count path has the same issue in principle if a shrinker omits\ncount_objects().\n\nTo fix it, only create \"count\" and \"scan\" debugfs files when the\ncorresponding callbacks are present."
    }
  ],
  "lastModified": "2026-09-04T15:24:56.173",
  "configurations": [
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}