GHSA-MPF7-XMX2-FRHW

Vulnerability from github – Published: 2026-07-25 12:31 – Updated: 2026-07-27 06:30
VLAI
Details

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

udf: validate free block extents against the partition length

udf_free_blocks() checks the logical block number and count against the partition length, but drops the extent offset from that final bound. A crafted extent can pass the guard while logicalBlockNum + offset + count points past the partition, which later indexes past the space bitmap array.

A single ftruncate(2) on a file backed by such an extent reliably panics the kernel. This is a local availability issue. On desktop systems where UDisks/polkit allows the active user to mount removable UDF media without CAP_SYS_ADMIN, an unprivileged local user can supply the crafted filesystem and trigger the panic by truncating a writable file on it. Systems that require root or CAP_SYS_ADMIN to mount the image have a higher prerequisite.

No confidentiality or integrity impact is claimed: the reproduced primitive is an out-of-bounds read of a bitmap pointer slot followed by a kernel panic.

Use the already computed logicalBlockNum + offset + count value for the partition length check. Also make load_block_bitmap() reject an out-of-range block group before indexing s_block_bitmap[], so corrupted callers cannot walk past the flexible array.

Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
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{
  "affected": [],
  "aliases": [
    "CVE-2026-64324"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-07-25T10:17:13Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nudf: validate free block extents against the partition length\n\nudf_free_blocks() checks the logical block number and count against the\npartition length, but drops the extent offset from that final bound.  A\ncrafted extent can pass the guard while logicalBlockNum + offset + count\npoints past the partition, which later indexes past the space bitmap\narray.\n\nA single ftruncate(2) on a file backed by such an extent reliably\npanics the kernel.  This is a local availability issue.  On desktop\nsystems where UDisks/polkit allows the active user to mount removable\nUDF media without CAP_SYS_ADMIN, an unprivileged local user can supply\nthe crafted filesystem and trigger the panic by truncating a writable\nfile on it.  Systems that require root or CAP_SYS_ADMIN to mount the\nimage have a higher prerequisite.\n\nNo confidentiality or integrity impact is claimed: the reproduced\nprimitive is an out-of-bounds read of a bitmap pointer slot followed by\na kernel panic.\n\nUse the already computed logicalBlockNum + offset + count value for the\npartition length check.  Also make load_block_bitmap() reject an\nout-of-range block group before indexing s_block_bitmap[], so corrupted\ncallers cannot walk past the flexible array.",
  "id": "GHSA-mpf7-xmx2-frhw",
  "modified": "2026-07-27T06:30:33Z",
  "published": "2026-07-25T12:31:31Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-64324"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/12af328d2ee8d68e81ba612246d0b54b22d23e1f"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/335202ab25b01fdd45889ff25eab70864686dea3"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/5f0419457f89dce1a3f1c8e62a3adf2f39ab8168"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9442d75429b0c556292a7454fe888d54259f5240"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b54aee5652fcd7c23a0904a4623ec462c3edc70c"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/be87de7789a82a030a4896bc7683415ec9fa6f2b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/fb49099206c5c57af28a157249fa7bcb5518f99e"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/fdd6229d2ae9914c1f25d1041db0f4f312a4fa76"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}



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