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CVE-2026-89664

Estado: RecibidaAlta (7.5)—

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

nfsd: release OPEN-decoded posix ACLs via op_release

nfsd4_decode_createhow4() calls nfsd4_decode_fattr4(), which allocates refcounted struct posix_acl objects via posix_acl_alloc() and stores them in open->op_pacl and open->op_dpacl. These pointers must be released once the OPEN compound finishes.

When nfsd4_decode_open_claim4() returns a non-seqid-mutating error, the dispatcher short-circuits before op_func runs:

Before this change OP_OPEN had no .op_release in nfsd4_ops[], and the release pair lived inside nfsd4_open() at its out_err: label.

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On the short-circuit path nfsd4_open() is never invoked, so both posix_acl refs leak on every malformed OPEN compound that carries valid POSIX ACL createhow4 attributes.

Add nfsd4_open_release() and wire it as .op_release for OP_OPEN. posix_acl_release() is NULL-safe, so the single release site covers both the normal path and the nfsd4_open_omfg short-circuit. Remove the matching posix_acl_release() pair from nfsd4_open()'s out_err: label to avoid double-releasing.

The compound loop has two encoding branches: nfsd4_encode_operation() for normal ops, and nfsd4_encode_replay() for v4.0 replayed ops. op_release was only called from nfsd4_encode_operation(), so resources attached to op->u leak on the replay path.

Move the op_release() call out of nfsd4_encode_operation() and the replay branch, placing it after the if-else in nfsd4_proc_compound(). This gives a single call site in a fairly obviously-correct place, covering both the normal encoding and replay paths.

Detalles técnicos trazas, registros y código del informe original
    nfsd4_proc_compound()
      if (op->status && op->opnum == OP_OPEN)
          op->status = nfsd4_open_omfg(...)
              if (!seqid_mutating_err(ntohl(op->status)))
                  return op->status;   /* nfsd4_open() never runs */
      ...
      opdesc->op_release(&op->u)  /* must still release op_pacl/op_dpacl */

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.

Inferido por reglas deterministas a partir del vector CVSS y la CWE. Solo orientativo.

🛡️ 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)

Mostrar
{
  "id": "CVE-2026-89664",
  "cveTags": [],
  "metrics": {
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 7.5,
          "attackVector": "NETWORK",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
          "integrityImpact": "NONE",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "NONE"
        },
        "impactScore": 3.6,
        "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": "5fc51dfc2eb160bd7ab3251ab1767cacf9c8bf05",
              "lessThan": "5b3a7d7c23c071efe12dd1bc1d2e5f97c4892921",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "5fc51dfc2eb160bd7ab3251ab1767cacf9c8bf05",
              "lessThan": "8215892993ea9f5231da4fa9eb42428a286fce8b",
              "versionType": "git"
            }
          ],
          "programFiles": [
            "fs/nfsd/nfs4proc.c",
            "fs/nfsd/nfs4xdr.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "7.0"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "7.0",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "7.2.4",
              "versionType": "semver",
              "lessThanOrEqual": "7.2.*"
            },
            {
              "status": "unaffected",
              "version": "7.3-rc1",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "fs/nfsd/nfs4proc.c",
            "fs/nfsd/nfs4xdr.c"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2026-09-11T20:19:52.790",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/5b3a7d7c23c071efe12dd1bc1d2e5f97c4892921",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/8215892993ea9f5231da4fa9eb42428a286fce8b",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Received",
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: release OPEN-decoded posix ACLs via op_release\n\nnfsd4_decode_createhow4() calls nfsd4_decode_fattr4(), which allocates\nrefcounted struct posix_acl objects via posix_acl_alloc() and stores\nthem in open->op_pacl and open->op_dpacl. These pointers must be\nreleased once the OPEN compound finishes.\n\nWhen nfsd4_decode_open_claim4() returns a non-seqid-mutating error,\nthe dispatcher short-circuits before op_func runs:\n\n    nfsd4_proc_compound()\n      if (op->status && op->opnum == OP_OPEN)\n          op->status = nfsd4_open_omfg(...)\n              if (!seqid_mutating_err(ntohl(op->status)))\n                  return op->status;   /* nfsd4_open() never runs */\n      ...\n      opdesc->op_release(&op->u)  /* must still release op_pacl/op_dpacl */\n\nBefore this change OP_OPEN had no .op_release in nfsd4_ops[], and the\nrelease pair lived inside nfsd4_open() at its out_err: label. On the\nshort-circuit path nfsd4_open() is never invoked, so both posix_acl\nrefs leak on every malformed OPEN compound that carries valid POSIX\nACL createhow4 attributes.\n\nAdd nfsd4_open_release() and wire it as .op_release for OP_OPEN.\nposix_acl_release() is NULL-safe, so the single release site covers\nboth the normal path and the nfsd4_open_omfg short-circuit. Remove\nthe matching posix_acl_release() pair from nfsd4_open()'s out_err:\nlabel to avoid double-releasing.\n\nThe compound loop has two encoding branches: nfsd4_encode_operation()\nfor normal ops, and nfsd4_encode_replay() for v4.0 replayed ops.\nop_release was only called from nfsd4_encode_operation(), so resources\nattached to op->u leak on the replay path.\n\nMove the op_release() call out of nfsd4_encode_operation() and the\nreplay branch, placing it after the if-else in nfsd4_proc_compound().\nThis gives a single call site in a fairly obviously-correct place,\ncovering both the normal encoding and replay paths."
    }
  ],
  "lastModified": "2026-09-13T07:17:32.047",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}