CVE-2026-53397 (GCVE-0-2026-53397)
Vulnerability from cvelistv5
Published
2026-07-19 12:01
Modified
2026-08-17 04:50
Severity ?
7.5 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: nfsd: fix posix_acl leak on SETACL decode failure nfsaclsvc_decode_setaclargs() and nfs3svc_decode_setaclargs() each call nfs_stream_decode_acl() twice, first for NFS_ACL and then for NFS_DFACL. Each successful call transfers ownership of a freshly allocated posix_acl into argp->acl_access or argp->acl_default. If the first call succeeds but the second fails, the decoder returns false and argp->acl_access is left dangling. ACLPROC2_SETACL.pc_release was wired to nfssvc_release_attrstat and ACLPROC3_SETACL.pc_release was wired to nfs3svc_release_fhandle. Both only call fh_put() and have no knowledge of the ACL fields on argp. The posix_acl_release() pairs sat at the out: labels inside nfsacld_proc_setacl() and nfsd3_proc_setacl(), but svc_process() skips pc_func when pc_decode returns false, so that cleanup is unreachable on decode failure: svc_process_common() pc_decode() /* decode_setaclargs: false */ /* pc_func skipped */ pc_release() /* fh_put only -- ACLs leaked */ The orphaned posix_acl is leaked for the lifetime of the server. Fix by adding nfsaclsvc_release_setacl() and nfs3svc_release_setacl(), which release both argp->acl_access and argp->acl_default in addition to fh_put(), and wiring them as pc_release for their respective SETACL procedures. pc_release runs on every path svc_process() takes after decode, including decode failure, so the posix_acl_release() pairs are removed from the proc functions' out: labels to keep ownership in one place. This matches the existing release_getacl() pattern used by the sibling GETACL procedures.
References
Impacted products
Vendor Product Version
Linux Linux Version: a257cdd0e2179630d3201c32ba14d7fcb3c3a055
Version: a257cdd0e2179630d3201c32ba14d7fcb3c3a055
Version: a257cdd0e2179630d3201c32ba14d7fcb3c3a055
Version: a257cdd0e2179630d3201c32ba14d7fcb3c3a055
Version: a257cdd0e2179630d3201c32ba14d7fcb3c3a055
Version: a257cdd0e2179630d3201c32ba14d7fcb3c3a055
Version: a257cdd0e2179630d3201c32ba14d7fcb3c3a055
Version: a257cdd0e2179630d3201c32ba14d7fcb3c3a055
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/nfsd/nfs2acl.c",
            "fs/nfsd/nfs3acl.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/nfsd/nfs2acl.c",
            "fs/nfsd/nfs3acl.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "2.6.13"
            },
            {
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.10.*",
              "status": "unaffected",
              "version": "5.10.260",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.211",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.177",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.144",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.95",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.38",
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            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.3",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
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                  "vulnerable": true
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                  "versionEndExcluding": "5.15.211",
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                  "vulnerable": true
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                  "versionEndExcluding": "6.1.177",
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                  "vulnerable": true
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.144",
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                  "vulnerable": true
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                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                  "vulnerable": true
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                  "versionEndExcluding": "7.2",
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                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: fix posix_acl leak on SETACL decode failure\n\nnfsaclsvc_decode_setaclargs() and nfs3svc_decode_setaclargs() each\ncall nfs_stream_decode_acl() twice, first for NFS_ACL and then for\nNFS_DFACL.  Each successful call transfers ownership of a freshly\nallocated posix_acl into argp-\u003eacl_access or argp-\u003eacl_default.  If\nthe first call succeeds but the second fails, the decoder returns\nfalse and argp-\u003eacl_access is left dangling.\n\nACLPROC2_SETACL.pc_release was wired to nfssvc_release_attrstat and\nACLPROC3_SETACL.pc_release was wired to nfs3svc_release_fhandle.\nBoth only call fh_put() and have no knowledge of the ACL fields on\nargp.  The posix_acl_release() pairs sat at the out: labels inside\nnfsacld_proc_setacl() and nfsd3_proc_setacl(), but svc_process()\nskips pc_func when pc_decode returns false, so that cleanup is\nunreachable on decode failure:\n\n    svc_process_common()\n      pc_decode()                  /* decode_setaclargs: false */\n      /* pc_func skipped */\n      pc_release()                 /* fh_put only -- ACLs leaked */\n\nThe orphaned posix_acl is leaked for the lifetime of the server.\n\nFix by adding nfsaclsvc_release_setacl() and nfs3svc_release_setacl(),\nwhich release both argp-\u003eacl_access and argp-\u003eacl_default in addition\nto fh_put(), and wiring them as pc_release for their respective SETACL\nprocedures.  pc_release runs on every path svc_process() takes after\ndecode, including decode failure, so the posix_acl_release() pairs are\nremoved from the proc functions\u0027 out: labels to keep ownership in one\nplace.  This matches the existing release_getacl() pattern used by\nthe sibling GETACL procedures."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.5,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - The vulnerable code is in nfsd\u0027s NFS ACL program (RPC program 100227), reachable over the network via the in-kernel NFS server on TCP/UDP port 2049 when NFSD ACL support is enabled.\nAC:L - Once nfsd with ACL support is running, an attacker can reliably trigger the leak by sending a SETACL RPC with mask including both NFS_ACL and NFS_DFACL, a valid first ACL, and a malformed second ACL that fails decode.\nPR:N - Exploitation requires only network access as an NFS client with RPC credentials (AUTH_UNIX is spoofable) from a source IP matching an export entry; no local shell or real root on the server is needed.\nUI:N - Triggering the leak requires only crafted NFS ACL RPC packets; no victim user action such as mounting a filesystem or opening a file is required.\nS:U - The impact is confined to kernel memory consumption within the nfsd server context and does not cross a security boundary such as a VM, container, or IOMMU isolation boundary.\nC:N - This is a kmalloc leak of attacker-supplied ACL data with no out-of-bounds read, use-after-free, or other mechanism that exposes kernel memory to the attacker.\nI:N - The bug orphans allocated posix_acl objects without modifying file data, ACLs on disk, or any other integrity-protected resources.\nA:H - Each trigger permanently leaks a posix_acl allocation (up to ~16KB with max entries) for the server\u0027s lifetime; repeated remote SETACL requests can exhaust kernel memory and deny service to the NFS server and co-hosted workloads."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T04:50:49.240Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/b2eb1ffd511d1b3c3e21122f97cbbccea411e277"
        },
        {
          "url": "https://git.kernel.org/stable/c/b94c4be77682aab06d65ca7296149e3bcfb37353"
        },
        {
          "url": "https://git.kernel.org/stable/c/887f92ceccf3eacd5f2402db21254d66372fae00"
        },
        {
          "url": "https://git.kernel.org/stable/c/1e96239fddcefacf6afe6c498357be68eacbcabc"
        },
        {
          "url": "https://git.kernel.org/stable/c/bd69a825485168ef74e815ecb286754b570fdcc7"
        },
        {
          "url": "https://git.kernel.org/stable/c/136b416593f1349cf6f72c8e3d18f0f204ee8545"
        },
        {
          "url": "https://git.kernel.org/stable/c/a5b42c1e4ff2befaa6b96f7cbf32174751eba083"
        },
        {
          "url": "https://git.kernel.org/stable/c/0853ac544c590880d797b04daa33fcb72b6be0e1"
        }
      ],
      "title": "nfsd: fix posix_acl leak on SETACL decode failure",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-53397",
    "datePublished": "2026-07-19T12:01:58.938Z",
    "dateReserved": "2026-06-09T07:44:35.402Z",
    "dateUpdated": "2026-08-17T04:50:49.240Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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