CVE-2026-90104 (GCVE-0-2026-90104)
Vulnerability from cvelistv5
Published
2026-09-17 16:06
Modified
2026-10-21 12:49
Severity ?
9.8 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
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.
References
Impacted products
Vendor Product Version
Linux Linux Version: 4aece6a19cf7f474f15eb861ba74db4479884ce3
Version: 4aece6a19cf7f474f15eb861ba74db4479884ce3
Version: 4aece6a19cf7f474f15eb861ba74db4479884ce3
Version: 4aece6a19cf7f474f15eb861ba74db4479884ce3
Version: 4aece6a19cf7f474f15eb861ba74db4479884ce3
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/nfs/callback_xdr.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "status": "affected",
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              "versionType": "git"
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              "versionType": "git"
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              "version": "4aece6a19cf7f474f15eb861ba74db4479884ce3",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/nfs/callback_xdr.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "2.6.31"
            },
            {
              "lessThan": "2.6.31",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.160",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.114",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.57",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.6",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.160",
                  "versionStartIncluding": "2.6.31",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.114",
                  "versionStartIncluding": "2.6.31",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.57",
                  "versionStartIncluding": "2.6.31",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.6",
                  "versionStartIncluding": "2.6.31",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3",
                  "versionStartIncluding": "2.6.31",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "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": [
        {
          "cvssV3_1": {
            "baseScore": 9.8,
            "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."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-21T12:49:51.551Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/ed54460caf5b5aa65ec03c9a6032d831f39f19f5"
        },
        {
          "url": "https://git.kernel.org/stable/c/7510a5b9edec9d9536a4e69f10edfb2592e6cf7f"
        },
        {
          "url": "https://git.kernel.org/stable/c/f4d23937e1c41995c2f54af26c89b5e48a41c299"
        },
        {
          "url": "https://git.kernel.org/stable/c/f31f3c042e024aef437cda42f0424ae8d4594b6c"
        },
        {
          "url": "https://git.kernel.org/stable/c/8fa4804fe62ca4155a2d8fc2789d630376cbf2fc"
        }
      ],
      "title": "NFSv4.1: zero referring call lists before decoding",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "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"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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