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CVE-2026-90042

Estado: RecibidaCrítica (9.8)—

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

ceph: properly decrypt filenames in vmalloc() buffers

The fscrypt subsystem uses the scatterlist crypto API, inheriting its requirement that any buffers are in the linear mapping region. However, the messenger client uses kvmalloc() to create buffers for messages, which will occasionally place those buffers in the vmalloc() region when physical memory fragmentation doesn't permit a large enough kmalloc(). The various callers of ceph_fname_to_usr() directly pass (slices of) raw messages from the MDS without considering that the messages may be in vmalloc() buffers, resulting in oopses especially on non-x86 platforms (see 'Closes:' for more details and a reproducer).

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Make ceph_fname_to_usr() explicitly tolerant of vmalloc()-allocated fname->ctext, fname->name, and/or oname->name buffers, using `tname` (which, when non-null, must be a linear address; when null, is briefly allocated as necessary) as a bounce buffer to avoid passing any inappropriate addresses to fscrypt_fname_disk_to_usr().

Additionally change parse_reply_info_readdir() -- the only function to supply its own `tname` -- to follow the new "tname must never come from vmalloc()" rule by passing NULL when the message is not in the linear region. Though this causes a per-dentry kmalloc()+kfree(), this overhead exists only when processing the minority of messages that spill into vmalloc(). My (crude) testing puts this at only about 1 in 8,000 readdir messages. Still, if the overhead proves unreasonable in the future, it is easy enough to mitigate: a future change could allocate a bounce buffer in parse_reply_info_readdir() and use that as `tname` instead.

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.

Vector crítico AV:N/PR:N/UI:N indica exploración remota sin privilegios de kernel Linux. El fallo permite DoS (oopses/panic) al enviar mensajes MDS con buffers en vmalloc() que causan fallos en criptografía. Potencial ejecución limitada por escalada post-exploit.

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

Filter Network TrafficVulnerability ScanningPrivileged Account ManagementNetwork SegmentationLimit Access to Resource Over NetworkApplication Isolation and Sandboxing

Tecnologías afectadas (1)

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

Linux — Linux KernelAI

Referencias

JSON original (NVD)

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{
  "id": "CVE-2026-90042",
  "cveTags": [],
  "metrics": {
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 9.8,
          "attackVector": "NETWORK",
          "baseSeverity": "CRITICAL",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "HIGH"
        },
        "impactScore": 5.9,
        "exploitabilityScore": 3.9
      }
    ]
  },
  "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": "457117f077c6749d1e28469eae91fb69c9806768",
              "lessThan": "93729594af506557a86f8b603be7ac5f3370eeca",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "457117f077c6749d1e28469eae91fb69c9806768",
              "lessThan": "110747ff535e3d98ac17d68dbd056bb6ef000e23",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "457117f077c6749d1e28469eae91fb69c9806768",
              "lessThan": "3b467c68803d7c7e82678289e598afd44faa6101",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "457117f077c6749d1e28469eae91fb69c9806768",
              "lessThan": "e939fc6a7bd969a58a150b7f188c1047138403e3",
              "versionType": "git"
            }
          ],
          "programFiles": [
            "fs/ceph/crypto.c",
            "fs/ceph/mds_client.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.6"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "6.6",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "6.12.111",
              "versionType": "semver",
              "lessThanOrEqual": "6.12.*"
            },
            {
              "status": "unaffected",
              "version": "6.18.51",
              "versionType": "semver",
              "lessThanOrEqual": "6.18.*"
            },
            {
              "status": "unaffected",
              "version": "7.2.5",
              "versionType": "semver",
              "lessThanOrEqual": "7.2.*"
            },
            {
              "status": "unaffected",
              "version": "7.3-rc1",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "fs/ceph/crypto.c",
            "fs/ceph/mds_client.c"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2026-09-16T11:17:17.450",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/110747ff535e3d98ac17d68dbd056bb6ef000e23",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/3b467c68803d7c7e82678289e598afd44faa6101",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/93729594af506557a86f8b603be7ac5f3370eeca",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/e939fc6a7bd969a58a150b7f188c1047138403e3",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Received",
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nceph: properly decrypt filenames in vmalloc() buffers\n\nThe fscrypt subsystem uses the scatterlist crypto API, inheriting its\nrequirement that any buffers are in the linear mapping region. However,\nthe messenger client uses kvmalloc() to create buffers for messages,\nwhich will occasionally place those buffers in the vmalloc() region when\nphysical memory fragmentation doesn't permit a large enough kmalloc().\nThe various callers of ceph_fname_to_usr() directly pass (slices of) raw\nmessages from the MDS without considering that the messages may be in\nvmalloc() buffers, resulting in oopses especially on non-x86 platforms\n(see 'Closes:' for more details and a reproducer).\n\nMake ceph_fname_to_usr() explicitly tolerant of vmalloc()-allocated\nfname->ctext, fname->name, and/or oname->name buffers, using `tname`\n(which, when non-null, must be a linear address; when null, is briefly\nallocated as necessary) as a bounce buffer to avoid passing any\ninappropriate addresses to fscrypt_fname_disk_to_usr().\n\nAdditionally change parse_reply_info_readdir() -- the only function to\nsupply its own `tname` -- to follow the new \"tname must never come from\nvmalloc()\" rule by passing NULL when the message is not in the linear\nregion. Though this causes a per-dentry kmalloc()+kfree(), this overhead\nexists only when processing the minority of messages that spill into\nvmalloc(). My (crude) testing puts this at only about 1 in 8,000 readdir\nmessages. Still, if the overhead proves unreasonable in the future, it\nis easy enough to mitigate: a future change could allocate a bounce\nbuffer in parse_reply_info_readdir() and use that as `tname` instead."
    }
  ],
  "lastModified": "2026-09-21T14:17:28.387",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}