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NFSv4/pNFS: reject zero-length r_addr in nfs4_decode_mp_ds_addr

Type: advisorySources: OSV

In the Linux kernel, the following vulnerability has been resolved: NFSv4/pNFS: reject zero-length r_addr in nfs4_decode_mp_ds_addr nfs4_decode_mp_ds_addr() decodes the r_netid and r_addr opaques of a netaddr4 from a GETDEVICEINFO multipath-DS body, then immediately calls strrchr(buf, '.') to locate the port separator. Both decodes use xdr_stream_decode_string_dup(), and the current code checks only "nlen < 0" / "rlen < 0" before dereferencing the returned string. When the on-wire opaque has length zero, xdr_stream_decode_opaque_inline() returns 0 and xdr_stream_decode_string_dup() falls through to its "*str = NULL; return ret" tail, leaving buf NULL with a return value of 0. The "< 0" check does not catch this, and the next line is strrchr(NULL, '.'), a kernel NULL pointer dereference reachable from any pNFS-flexfile client mounted against a malicious or compromised metadata server. Reject the zero-length cases explicitly so the decoder fails with -EBADMSG (treated as a malformed GETDEVICEINFO body) instead of panicking the client.

Products
Kernel
Affected versions
Not specified
Fixed versions
5.15.211, 6.1.177, 6.12.95, 6.18.38, 6.6.144, 7.1.3
CVEs
CVE-2026-53391
Confirmed fixed CVEs
Not specified
Updated in this feed
3 Nov 2026, 16:16 UTC · Revision 1

Source evidence

NFSv4/pNFS: reject zero-length r_addr in nfs4_decode_mp_ds_addr

core-osv · Original source

Published 19 Jul 2026, 12:01 UTC

In the Linux kernel, the following vulnerability has been resolved: NFSv4/pNFS: reject zero-length r_addr in nfs4_decode_mp_ds_addr nfs4_decode_mp_ds_addr() decodes the r_netid and r_addr opaques of a netaddr4 from a GETDEVICEINFO multipath-DS body, then immediately calls strrchr(buf, '.') to locate the port separator. Both decodes use xdr_stream_decode_string_dup(), and the current code checks only "nlen < 0" / "rlen < 0" before dereferencing the returned string. When the on-wire opaque has length zero, xdr_stream_decode_opaque_inline() returns 0 and xdr_stream_decode_string_dup() falls through to its "*str = NULL; return ret" tail, leaving buf NULL with a return value of 0. The "< 0" check does not catch this, and the next line is strrchr(NULL, '.'), a kernel NULL pointer dereference reachable from any pNFS-flexfile client mounted against a malicious or compromised metadata server. Reject the zero-length cases explicitly so the decoder fails with -EBADMSG (treated as a malformed GETDEVICEINFO body) instead of panicking the client.

osv:CVE-2026-53391

Kernel

Fixed versions: 5.15.211, 6.1.177, 6.6.144, 6.12.95, 6.18.38, 7.1.3

Complete source record
{
  "id": "47a5a2e32e55a57c9836aff816fbea3c0c8ba445d4399077997626e1ef7356ae",
  "url": "https://osv.dev/vulnerability/CVE-2026-53391",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "NFSv4/pNFS: reject zero-length r_addr in nfs4_decode_mp_ds_addr",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: NFSv4/pNFS: reject zero-length r_addr in nfs4_decode_mp_ds_addr nfs4_decode_mp_ds_addr() decodes the r_netid and r_addr opaques of a netaddr4 from a GETDEVICEINFO multipath-DS body, then immediately calls strrchr(buf, '.') to locate the port separator. Both decodes use xdr_stream_decode_string_dup(), and the current code checks only \"nlen < 0\" / \"rlen < 0\" before dereferencing the returned string. When the on-wire opaque has length zero, xdr_stream_decode_opaque_inline() returns 0 and xdr_stream_decode_string_dup() falls through to its \"*str = NULL; return ret\" tail, leaving buf NULL with a return value of 0. The \"< 0\" check does not catch this, and the next line is strrchr(NULL, '.'), a kernel NULL pointer dereference reachable from any pNFS-flexfile client mounted against a malicious or compromised metadata server. Reject the zero-length cases explicitly so the decoder fails with -EBADMSG (treated as a malformed GETDEVICEINFO body) instead of panicking the client.",
    "evidence": "osv:CVE-2026-53391",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "5.15.211",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.1.177",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.6.144",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.12.95",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.18.38",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "7.1.3",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-53391",
      "aliases": [
        "CVE-2026-53391"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
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                  "introduced": "6b7f3cf96364eaf597940cb5c68a682894829915"
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                {
                  "fixed": "76b94cbd32aacf36a641956385a852635c6802b9"
                },
                {
                  "fixed": "c8e4e0c701d0192a2efb6df059c0f9e19678c23d"
                },
                {
                  "fixed": "6c344fff2feff9d4d716d8e4ad40e9b5040ee5ea"
                },
                {
                  "fixed": "427ab81a811dab4bca9d19f82eec5847ae42646e"
                },
                {
                  "fixed": "012d37a568bfbb2c9686f03ade75560bc7139956"
                },
                {
                  "fixed": "30aae62e50b4e074a90a9a5e15246548fbdc1182"
                },
                {
                  "fixed": "41fe0f7b84f0cb822ae10ab08592996a592b2a25"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-53391.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "4.0.0"
                },
                {
                  "fixed": "5.15.211"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.16.0"
                },
                {
                  "fixed": "6.1.177"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.2.0"
                },
                {
                  "fixed": "6.6.144"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.7.0"
                },
                {
                  "fixed": "6.12.95"
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              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.13.0"
                },
                {
                  "fixed": "6.18.38"
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              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.19.0"
                },
                {
                  "fixed": "7.1.3"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-53391.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:30.155956421Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/012d37a568bfbb2c9686f03ade75560bc7139956",
        "https://git.kernel.org/stable/c/30aae62e50b4e074a90a9a5e15246548fbdc1182",
        "https://git.kernel.org/stable/c/41fe0f7b84f0cb822ae10ab08592996a592b2a25",
        "https://git.kernel.org/stable/c/427ab81a811dab4bca9d19f82eec5847ae42646e",
        "https://git.kernel.org/stable/c/6c344fff2feff9d4d716d8e4ad40e9b5040ee5ea",
        "https://git.kernel.org/stable/c/76b94cbd32aacf36a641956385a852635c6802b9",
        "https://git.kernel.org/stable/c/c8e4e0c701d0192a2efb6df059c0f9e19678c23d",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/53xxx/CVE-2026-53391.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-53391",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/53xxx/CVE-2026-53391.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-53391",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 497247,
  "published_at": "2026-07-19T12:01:55.521+00:00"
}