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CVE-2026-64057

Estado: AnalizadaAlta (7.8)—

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

afs: Fix the locking used by afs_get_link()

The afs filesystem in the kernel doesn't do locking correctly for symbolic links. There are a number of problems:

Fix this by the following means:

Detalles técnicos trazas, registros y código del informe original
 (1) It doesn't do any locking around afs_read_single() to prevent races
     between multiple ->get_link() calls, thereby allowing the possibility
     of leaks.

 (2) It doesn't use RCU barriering when accessing the buffer pointers
     during RCU pathwalk.

 (3) It can race with another thread updating the contents of the symlink
     if a third party updated it on the server.

 (0) Move symlink handling into its own file as this makes it more
     complicated.

 (1) Take the validate_lock around afs_read_single() to prevent races
     between multiple ->get_link() calls.

 (2) Keep a separate copy of the symlink contents with an rcu_head.  This
     is always going to be a lot smaller than a page, so it can be
     kmalloc'd and save quite a bit of memory.  It also needs a refcount
     for non-RCU pathwalk.

 (3) Split the symlink read and write-to-cache routines in afs from those
     for directories.

 (4) Discard the I/O buffer as soon as the write-to-cache completes as this
     is a full page (plus a folio_queue).

 (5) If there's no cache, discard the I/O buffer immediately after reading
     and copying if there is no cache.

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).

🎯 Técnicas ATT&CK

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

Escalada local de privilegios en kernel Linux (AV:L, PR:L) mediante race conditions en symlinks de afs; acceso a contenidos de buffer y corrupción de datos de enlaces simbólicos.

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 ProgramRestrict File and Directory PermissionsRemote Data StorageExecution PreventionEncrypt Sensitive InformationApplication Isolation and Sandboxing

Tecnologías afectadas (1)

Linux — Linux Kernel

CWE

Referencias

JSON original (NVD)

Mostrar
{
  "id": "CVE-2026-64057",
  "cveTags": [],
  "metrics": {
    "cvssMetricV31": [
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        "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"
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        "impactScore": 5.9,
        "exploitabilityScore": 1.8
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          "product": "Linux",
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            "fs/afs/fsclient.c",
            "fs/afs/inode.c",
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            "fs/afs/symlink.c",
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            },
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          ],
          "programFiles": [
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            "fs/afs/dir.c",
            "fs/afs/fsclient.c",
            "fs/afs/inode.c",
            "fs/afs/internal.h",
            "fs/afs/symlink.c",
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            "fs/afs/yfsclient.c"
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      ]
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  ],
  "published": "2026-07-19T16:17:46.187",
  "references": [
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      "tags": [
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    },
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      "source": "nvd@nist.gov",
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          "lang": "en",
          "value": "CWE-667"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nafs: Fix the locking used by afs_get_link()\n\nThe afs filesystem in the kernel doesn't do locking correctly for symbolic\nlinks.  There are a number of problems:\n\n (1) It doesn't do any locking around afs_read_single() to prevent races\n     between multiple ->get_link() calls, thereby allowing the possibility\n     of leaks.\n\n (2) It doesn't use RCU barriering when accessing the buffer pointers\n     during RCU pathwalk.\n\n (3) It can race with another thread updating the contents of the symlink\n     if a third party updated it on the server.\n\nFix this by the following means:\n\n (0) Move symlink handling into its own file as this makes it more\n     complicated.\n\n (1) Take the validate_lock around afs_read_single() to prevent races\n     between multiple ->get_link() calls.\n\n (2) Keep a separate copy of the symlink contents with an rcu_head.  This\n     is always going to be a lot smaller than a page, so it can be\n     kmalloc'd and save quite a bit of memory.  It also needs a refcount\n     for non-RCU pathwalk.\n\n (3) Split the symlink read and write-to-cache routines in afs from those\n     for directories.\n\n (4) Discard the I/O buffer as soon as the write-to-cache completes as this\n     is a full page (plus a folio_queue).\n\n (5) If there's no cache, discard the I/O buffer immediately after reading\n     and copying if there is no cache."
    }
  ],
  "lastModified": "2026-09-02T21:13:12.787",
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