CVE-2026-53391 (GCVE-0-2026-53391)

Vulnerability from cvelistv5 – Published: 2026-07-19 12:01 – Updated: 2026-07-20 13:39
VLAI
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.
Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 6b7f3cf96364eaf597940cb5c68a682894829915 , < 76b94cbd32aacf36a641956385a852635c6802b9 (git)
Affected: 6b7f3cf96364eaf597940cb5c68a682894829915 , < c8e4e0c701d0192a2efb6df059c0f9e19678c23d (git)
Affected: 6b7f3cf96364eaf597940cb5c68a682894829915 , < 6c344fff2feff9d4d716d8e4ad40e9b5040ee5ea (git)
Affected: 6b7f3cf96364eaf597940cb5c68a682894829915 , < 427ab81a811dab4bca9d19f82eec5847ae42646e (git)
Affected: 6b7f3cf96364eaf597940cb5c68a682894829915 , < 012d37a568bfbb2c9686f03ade75560bc7139956 (git)
Affected: 6b7f3cf96364eaf597940cb5c68a682894829915 , < 30aae62e50b4e074a90a9a5e15246548fbdc1182 (git)
Affected: 6b7f3cf96364eaf597940cb5c68a682894829915 , < 41fe0f7b84f0cb822ae10ab08592996a592b2a25 (git)
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Linux Linux Affected: 4.0
Unaffected: 0 , < 4.0 (semver)
Unaffected: 5.15.211 , ≤ 5.15.* (semver)
Unaffected: 6.1.177 , ≤ 6.1.* (semver)
Unaffected: 6.6.144 , ≤ 6.6.* (semver)
Unaffected: 6.12.95 , ≤ 6.12.* (semver)
Unaffected: 6.18.38 , ≤ 6.18.* (semver)
Unaffected: 7.1.3 , ≤ 7.1.* (semver)
Unaffected: 7.2-rc1 , ≤ * (original_commit_for_fix)
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{
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          "programFiles": [
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              "operator": "OR"
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nNFSv4/pNFS: reject zero-length r_addr in nfs4_decode_mp_ds_addr\n\nnfs4_decode_mp_ds_addr() decodes the r_netid and r_addr opaques of a\nnetaddr4 from a GETDEVICEINFO multipath-DS body, then immediately\ncalls strrchr(buf, \u0027.\u0027) to locate the port separator. Both decodes\nuse xdr_stream_decode_string_dup(), and the current code checks only\n\"nlen \u003c 0\" / \"rlen \u003c 0\" before dereferencing the returned string.\n\nWhen the on-wire opaque has length zero, xdr_stream_decode_opaque_inline()\nreturns 0 and xdr_stream_decode_string_dup() falls through to its\n\"*str = NULL; return ret\" tail, leaving buf NULL with a return value\nof 0. The \"\u003c 0\" check does not catch this, and the next line is\nstrrchr(NULL, \u0027.\u0027), a kernel NULL pointer dereference reachable from\nany pNFS-flexfile client mounted against a malicious or compromised\nmetadata server.\n\nReject the zero-length cases explicitly so the decoder fails with\n-EBADMSG (treated as a malformed GETDEVICEINFO body) instead of\npanicking the client."
        }
      ],
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            "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"
          }
        }
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        "dateUpdated": "2026-07-20T13:39:54.843Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
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        },
        {
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        }
      ],
      "title": "NFSv4/pNFS: reject zero-length r_addr in nfs4_decode_mp_ds_addr",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-53391",
    "datePublished": "2026-07-19T12:01:55.521Z",
    "dateReserved": "2026-06-09T07:44:35.402Z",
    "dateUpdated": "2026-07-20T13:39:54.843Z",
    "state": "PUBLISHED"
  },
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      "date": "2026-07-21",
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      "percentile": "0.38988"
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      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "NFSv4/pNFS: reject zero-length r_addr in nfs4_decode_mp_ds_addr",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-53391.json",
      "version": "2"
    },
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Both decodes\\nuse xdr_stream_decode_string_dup(), and the current code checks only\\n\\\"nlen \u003c 0\\\" / \\\"rlen \u003c 0\\\" before dereferencing the returned string.\\n\\nWhen the on-wire opaque has length zero, xdr_stream_decode_opaque_inline()\\nreturns 0 and xdr_stream_decode_string_dup() falls through to its\\n\\\"*str = NULL; return ret\\\" tail, leaving buf NULL with a return value\\nof 0. The \\\"\u003c 0\\\" check does not catch this, and the next line is\\nstrrchr(NULL, \u0027.\u0027), a kernel NULL pointer dereference reachable from\\nany pNFS-flexfile client mounted against a malicious or compromised\\nmetadata server.\\n\\nReject the zero-length cases explicitly so the decoder fails with\\n-EBADMSG (treated as a malformed GETDEVICEINFO body) instead of\\npanicking the client.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"fs/nfs/pnfs_nfs.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"6b7f3cf96364eaf597940cb5c68a682894829915\",\"lessThan\":\"76b94cbd32aacf36a641956385a852635c6802b9\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"6b7f3cf96364eaf597940cb5c68a682894829915\",\"lessThan\":\"c8e4e0c701d0192a2efb6df059c0f9e19678c23d\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"6b7f3cf96364eaf597940cb5c68a682894829915\",\"lessThan\":\"6c344fff2feff9d4d716d8e4ad40e9b5040ee5ea\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"6b7f3cf96364eaf597940cb5c68a682894829915\",\"lessThan\":\"427ab81a811dab4bca9d19f82eec5847ae42646e\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"6b7f3cf96364eaf597940cb5c68a682894829915\",\"lessThan\":\"012d37a568bfbb2c9686f03ade75560bc7139956\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"6b7f3cf96364eaf597940cb5c68a682894829915\",\"lessThan\":\"30aae62e50b4e074a90a9a5e15246548fbdc1182\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"6b7f3cf96364eaf597940cb5c68a682894829915\",\"lessThan\":\"41fe0f7b84f0cb822ae10ab08592996a592b2a25\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"fs/nfs/pnfs_nfs.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"4.0\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"4.0\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"5.15.211\",\"lessThanOrEqual\":\"5.15.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.1.177\",\"lessThanOrEqual\":\"6.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.6.144\",\"lessThanOrEqual\":\"6.6.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.95\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.38\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.1.3\",\"lessThanOrEqual\":\"7.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.2-rc1\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H\",\"baseScore\":7.5,\"baseSeverity\":\"HIGH\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"NONE\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":3.9,\"impactScore\":3.6}]},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/012d37a568bfbb2c9686f03ade75560bc7139956\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/30aae62e50b4e074a90a9a5e15246548fbdc1182\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/41fe0f7b84f0cb822ae10ab08592996a592b2a25\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/427ab81a811dab4bca9d19f82eec5847ae42646e\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/6c344fff2feff9d4d716d8e4ad40e9b5040ee5ea\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/76b94cbd32aacf36a641956385a852635c6802b9\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/c8e4e0c701d0192a2efb6df059c0f9e19678c23d\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-07-20T17:10:44+00:00",
      "cve": "CVE-2026-53391",
      "id": "CVE-2026-53391",
      "initial_release_date": "2026-07-19T00:00:00+00:00",
      "product_status:known_affected": "260",
      "product_status:known_not_affected": "15",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: NFSv4/pNFS: reject zero-length r_addr in nfs4_decode_mp_ds_addr",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-53391.json",
      "version": "3"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.