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CVE-2026-74591

Estado: RecibidaCrítica (9.8)—

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

mm/filemap: __filemap_add_folio() restore index before retrying

In __filemap_add_folio()'s split-a-conflict loop, xas_set_order() is applied repeatedly: each application modifies xas.xa_index, rounding it down according to the split_order attempted at that stage: and if all goes as intended, it eventually (or immediately) converges on an xas_try_split() to the required folio_order, with xas.xa_index now the same as index: then xas_store() puts the new folio into the xarray there.

But if a new node was needed, and GFP_NOWAIT allocation did not get one, the lock is dropped, xas_nomem() used to allocate, and sequence retried.

Leer descripción completaMostrar menos

If (that part of) the xarray is unchanged when the lock is reacquired, no problem. But what if the conflict was meanwhile resolved by another thread (perhaps even doing the same thing, inserting a folio at that same index)? Isn't there a danger of now putting our folio into the xarray at an intermediate rounded-down index? With !folio_contains() bug to follow, when CONFIG_DEBUG_VM=y is checking for that.

Fix this with an xas_set_order() to restore the original xas.xa_index at the bottom of the loop, so the retry does a full re-evaluation after reacquiring the lock, and cannot reach xas_store() with the wrong index.

Production was suffering from rare SIGILLs and SIGSEGVs, executable text found a page away from where it belonged, !folio_contains() bug hit when debug enabled: symptoms not seen since this patch went in.

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 AV:N sin PR/UI sugiere T1190 (remoto sin autenticación), pero es un bug de kernel de lógica en mm/filemap sin acceso remoto directo documentado. Impactos: DoS por SIGILL/SIGSEGV (corrupción de memoria) y potencial escalada si se alcanza ejecución arbitraria de código en contexto kernel.

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 TrafficApplication Isolation and SandboxingExploit ProtectionUpdate SoftwareVulnerability ScanningThreat Intelligence Program

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-2026-74591",
  "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": "200a89c159a7a416115e6e309183c82183bf98aa",
              "lessThan": "4917e3ebcab50f0265e8ca01c8567de4c4a47511",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "200a89c159a7a416115e6e309183c82183bf98aa",
              "lessThan": "267ecd2eb7759c26f1a026eb0a5b231071534c9c",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "200a89c159a7a416115e6e309183c82183bf98aa",
              "lessThan": "86da3f7e1e609e1e8bfbab198af68467c5a015a5",
              "versionType": "git"
            }
          ],
          "programFiles": [
            "mm/filemap.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.15"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "6.15",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "6.18.45",
              "versionType": "semver",
              "lessThanOrEqual": "6.18.*"
            },
            {
              "status": "unaffected",
              "version": "7.1.9",
              "versionType": "semver",
              "lessThanOrEqual": "7.1.*"
            },
            {
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "mm/filemap.c"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2026-08-22T16:16:31.353",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/267ecd2eb7759c26f1a026eb0a5b231071534c9c",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/4917e3ebcab50f0265e8ca01c8567de4c4a47511",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/86da3f7e1e609e1e8bfbab198af68467c5a015a5",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Received",
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm/filemap: __filemap_add_folio() restore index before retrying\n\nIn __filemap_add_folio()'s split-a-conflict loop, xas_set_order() is\napplied repeatedly: each application modifies xas.xa_index, rounding it\ndown according to the split_order attempted at that stage: and if all goes\nas intended, it eventually (or immediately) converges on an\nxas_try_split() to the required folio_order, with xas.xa_index now the\nsame as index: then xas_store() puts the new folio into the xarray there.\n\nBut if a new node was needed, and GFP_NOWAIT allocation did not get one,\nthe lock is dropped, xas_nomem() used to allocate, and sequence retried. \nIf (that part of) the xarray is unchanged when the lock is reacquired, no\nproblem.  But what if the conflict was meanwhile resolved by another\nthread (perhaps even doing the same thing, inserting a folio at that same\nindex)?  Isn't there a danger of now putting our folio into the xarray at\nan intermediate rounded-down index?  With !folio_contains() bug to follow,\nwhen CONFIG_DEBUG_VM=y is checking for that.\n\nFix this with an xas_set_order() to restore the original xas.xa_index at\nthe bottom of the loop, so the retry does a full re-evaluation after\nreacquiring the lock, and cannot reach xas_store() with the wrong index.\n\nProduction was suffering from rare SIGILLs and SIGSEGVs, executable text\nfound a page away from where it belonged, !folio_contains() bug hit when\ndebug enabled: symptoms not seen since this patch went in."
    }
  ],
  "lastModified": "2026-08-25T06:18:34.397",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}