CVE-2026-90104 (GCVE-0-2026-90104)

Vulnerability from cvelistv5 – Published: 2026-09-17 16:06 – Updated: 2026-10-21 12:49
VLAI
Title
NFSv4.1: zero referring call lists before decoding
Summary
In the Linux kernel, the following vulnerability has been resolved: NFSv4.1: zero referring call lists before decoding decode_cb_sequence_args() allocates csa_rclists with kmalloc_objs(), so each referring_call_list starts uninitialized. decode_rc_list() assigns rcl_refcalls only when rcl_nrefcalls is nonzero. A valid list with zero referring calls therefore leaves the pointer uninitialized, and nfs4_callback_sequence() later passes stale slab contents to kfree(). Allocate csa_rclists with kzalloc_objs() so every rcl_refcalls member is NULL from the beginning, including valid empty referring call lists.
Severity
9.8 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 7061 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 4aece6a19cf7f474f15eb861ba74db4479884ce3 , < ed54460caf5b5aa65ec03c9a6032d831f39f19f5 (git)
Affected: 4aece6a19cf7f474f15eb861ba74db4479884ce3 , < 7510a5b9edec9d9536a4e69f10edfb2592e6cf7f (git)
Affected: 4aece6a19cf7f474f15eb861ba74db4479884ce3 , < f4d23937e1c41995c2f54af26c89b5e48a41c299 (git)
Affected: 4aece6a19cf7f474f15eb861ba74db4479884ce3 , < f31f3c042e024aef437cda42f0424ae8d4594b6c (git)
Affected: 4aece6a19cf7f474f15eb861ba74db4479884ce3 , < 8fa4804fe62ca4155a2d8fc2789d630376cbf2fc (git)
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Linux Linux Affected: 2.6.31
Unaffected: 0 , < 2.6.31 (semver)
Unaffected: 6.6.160 , ≤ 6.6.* (semver)
Unaffected: 6.12.114 , ≤ 6.12.* (semver)
Unaffected: 6.18.57 , ≤ 6.18.* (semver)
Unaffected: 7.2.6 , ≤ 7.2.* (semver)
Unaffected: 7.3 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
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{
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          "vendor": "Linux",
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              "versionType": "original_commit_for_fix"
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nNFSv4.1: zero referring call lists before decoding\n\ndecode_cb_sequence_args() allocates csa_rclists with kmalloc_objs(), so\neach referring_call_list starts uninitialized. decode_rc_list() assigns\nrcl_refcalls only when rcl_nrefcalls is nonzero. A valid list with zero\nreferring calls therefore leaves the pointer uninitialized, and\nnfs4_callback_sequence() later passes stale slab contents to kfree().\n\nAllocate csa_rclists with kzalloc_objs() so every rcl_refcalls member is\nNULL from the beginning, including valid empty referring call lists."
        }
      ],
      "metrics": [
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          "cvssV3_1": {
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            "baseSeverity": "CRITICAL",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - xs_read_stream_call()/rpcrdma_bc_receive_call() deliver a backchannel RPC_CALL on the established NFSv4.1 TCP or RPC/RDMA session into nfs4_callback_compound \u2192 process_op \u2192 decode_cb_sequence_args(); the attacker-controlled bytes are the CB_SEQUENCE csa_nrclists and rcl_nrefcalls XDR fields sent by the NFS server.\nAC:L - A single well-formed CB_SEQUENCE with csa_nrclists\u22651 and decode_rc_list() seeing rcl_nrefcalls==0 skips the rcl_refcalls assignment and still returns 0; nfs4_callback_sequence() then kfree()s that stale pointer. Empty referring_call_list4 is valid RFC 5661 XDR, so no race or victim-only state is required.\nPR:N - nfs_callback_authenticate() accepts RPC_AUTH_UNIX on the NFSv4.1 backchannel, and decode_cb_sequence_args() runs in process_op() before nfs4_find_client_sessionid(); the connected NFS server needs no account or capability on the client to send CB_SEQUENCE.\nUI:N - After nfs4_init_callback() has attached the backchannel (boot-time, autofs, or Kubernetes NFSv4.1 mounts), the server unilaterally sends CB_SEQUENCE; nfs4_callback_sequence() kfree()s rcl_refcalls with no further victim open, mount, or click.\nS:U - kfree of the stale rcl_refcalls pointer corrupts the NFS client\u0027s kmalloc heap in the same host kernel; it does not cross a VM, IOMMU, or guest/host boundary.\nC:H - nfs4_callback_sequence() kfree()s uninitialized rcl_refcalls left by kmalloc_objs() of csa_rclists when rcl_nrefcalls was 0. A prior CB_SEQUENCE that allocated then freed rcl_refcalls can leave that pointer in the reused slab object, a heap double-free/UAF read primitive.\nI:H - The same kfree of stale rcl_refcalls is a slab double-free of the referring_call array (size chosen by the attacker\u0027s earlier nrefcalls). Reclaim or spraying a replacement object over that free yields an arbitrary kernel write / control-flow hijack primitive.\nA:H - kfree of a non-NULL garbage rcl_refcalls pointer from a successful decode_cb_sequence_args() of an empty referring_call_list causes SLUB to BUG, oops, or panic even when the double-free is not fully exploited."
            }
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        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-21T12:49:51.551Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
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          "url": "https://git.kernel.org/stable/c/ed54460caf5b5aa65ec03c9a6032d831f39f19f5"
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      "title": "NFSv4.1: zero referring call lists before decoding",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-90104",
    "datePublished": "2026-09-17T16:06:14.191Z",
    "dateReserved": "2026-09-11T19:38:34.786Z",
    "dateUpdated": "2026-10-21T12:49:51.551Z",
    "state": "PUBLISHED"
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      "date": "2026-10-23",
      "epss": "0.00635",
      "percentile": "0.49795"
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      "cve": "CVE-2026-90104",
      "id": "msrc_CVE-2026-90104",
      "initial_release_date": "2026-09-19T01:19:32.000Z",
      "product_status:known_affected": "3",
      "product_status:under_investigation": "1",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "NFSv4.1: zero referring call lists before decoding",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-90104.json",
      "version": "5"
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            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nNFSv4.1: zero referring call lists before decoding\n\ndecode_cb_sequence_args() allocates csa_rclists with kmalloc_objs(), so\neach referring_call_list starts uninitialized. decode_rc_list() assigns\nrcl_refcalls only when rcl_nrefcalls is nonzero. A valid list with zero\nreferring calls therefore leaves the pointer uninitialized, and\nnfs4_callback_sequence() later passes stale slab contents to kfree().\n\nAllocate csa_rclists with kzalloc_objs() so every rcl_refcalls member is\nNULL from the beginning, including valid empty referring call lists."
          }
        ],
        "id": "CVE-2026-90104",
        "lastModified": "2026-10-21T13:20:37.137",
        "metrics": {
          "cvssMetricV31": [
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                "attackComplexity": "LOW",
                "attackVector": "NETWORK",
                "availabilityImpact": "HIGH",
                "baseScore": 9.8,
                "baseSeverity": "CRITICAL",
                "confidentialityImpact": "HIGH",
                "integrityImpact": "HIGH",
                "privilegesRequired": "NONE",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
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        "vulnStatus": "Received"
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      "current_release_date": "2026-10-13T13:23:04+00:00",
      "cve": "CVE-2026-90104",
      "id": "CVE-2026-90104",
      "initial_release_date": "2026-09-17T00:00:00+00:00",
      "product_status:known_affected": "277",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: NFSv4.1: zero referring call lists before decoding",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-90104.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "important",
      "current_release_date": "2026-10-20T23:53:02Z",
      "cve": "CVE-2026-90104",
      "id": "CVE-2026-90104",
      "initial_release_date": "2026-09-18T00:21:25Z",
      "product_status:known_affected": "588",
      "product_status:recommended": "513",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-90104",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/2026/cve-2026-90104.json",
      "version": "13"
    }
  }
}



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