GHSA-5599-PVJX-Q3HC

Vulnerability from github – Published: 2026-05-28 12:30 – Updated: 2026-05-28 12:30
VLAI
Details

In the Linux kernel, the following vulnerability has been resolved:

isofs: validate block number from NFS file handle in isofs_export_iget

isofs_fh_to_dentry() and isofs_fh_to_parent() pass an attacker- controlled block number (ifid->block or ifid->parent_block) from the NFS file handle to isofs_export_iget(), which only rejects block == 0 before calling isofs_iget() and ultimately sb_bread(). A crafted file handle with fh_len sufficient to pass the check added by commit 0405d4b63d08 ("isofs: Prevent the use of too small fid") can still drive the server to read any in-range block on the backing device as if it were an iso_directory_record. That earlier fix was assigned CVE-2025-37780.

sb_bread() on an out-of-range block returns NULL cleanly via the EIO path, so there is no memory-safety violation. For in-range reads of adjacent-partition data on the same block device, the unrelated bytes end up in iso_inode_info fields that reach the NFS client as dentry metadata. The deployment surface (isofs exported over NFS from loop-mounted images) is narrow and requires an authenticated NFS peer, but the malformed-file-handle class is reportable as hardening next to the existing CVE-2025-37780 fix.

Reject block >= ISOFS_SB(sb)->s_nzones in isofs_export_iget() so the check covers both isofs_fh_to_dentry() and isofs_fh_to_parent() call sites with a single line.

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{
  "affected": [],
  "aliases": [
    "CVE-2026-46124"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-05-28T10:16:27Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nisofs: validate block number from NFS file handle in isofs_export_iget\n\nisofs_fh_to_dentry() and isofs_fh_to_parent() pass an attacker-\ncontrolled block number (ifid-\u003eblock or ifid-\u003eparent_block) from\nthe NFS file handle to isofs_export_iget(), which only rejects\nblock == 0 before calling isofs_iget() and ultimately sb_bread().\nA crafted file handle with fh_len sufficient to pass the check\nadded by commit 0405d4b63d08 (\"isofs: Prevent the use of too small\nfid\") can still drive the server to read any in-range block on the\nbacking device as if it were an iso_directory_record.  That earlier\nfix was assigned CVE-2025-37780.\n\nsb_bread() on an out-of-range block returns NULL cleanly via the\nEIO path, so there is no memory-safety violation.  For in-range\nreads of adjacent-partition data on the same block device, the\nunrelated bytes end up in iso_inode_info fields that reach the NFS\nclient as dentry metadata.  The deployment surface (isofs exported\nover NFS from loop-mounted images) is narrow and requires an\nauthenticated NFS peer, but the malformed-file-handle class is\nreportable as hardening next to the existing CVE-2025-37780 fix.\n\nReject block \u003e= ISOFS_SB(sb)-\u003es_nzones in isofs_export_iget() so\nthe check covers both isofs_fh_to_dentry() and isofs_fh_to_parent()\ncall sites with a single line.",
  "id": "GHSA-5599-pvjx-q3hc",
  "modified": "2026-05-28T12:30:29Z",
  "published": "2026-05-28T12:30:29Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-46124"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/0a1af74ae2177bda3aee0837a0546309aa539d0d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/24376458138387fb251e782e624c7776e9826796"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/4c721a1d9b3c4fcaf59cc9b2281e3ec5a043e1a6"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/afbafeddf23db13fe2edb2d5c0bf4bbb13d7881b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/bb0988ed4f2e26d59bbb58f644cb3a55b7521e21"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}


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