{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2026-63954",
  "modified": "2026-10-09T11:39:44Z",
  "upstream": [
    "CVE-2026-63954"
  ],
  "published": "2026-07-19T14:56:29Z",
  "summary": "hpfs: fix a crash if hpfs_map_dnode_bitmap fails",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nhpfs: fix a crash if hpfs_map_dnode_bitmap fails\n\nIf hpfs_map_dnode_bitmap fails, the code would call hpfs_brelse4 on\nuninitialized quad buffer head, causing a crash.",
  "severity": [
    {
      "type": "CVSS_V3",
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
    }
  ],
  "affected": [
    {
      "package": {
        "ecosystem": "Raspberry Pi OS:12",
        "name": "linux"
      },
      "versions": [
        "1:6.1.47-1+rpt4"
      ],
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-2712",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v6",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v7",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v7l",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v8",
            "binary_version": "1:6.1.47-1+rpt4"
          }
        ]
      },
      "database_specific": {
        "per_version": {
          "1:6.1.47-1+rpt4": {
            "linux_commit": "655fc658a15ae7a6f37103754adb39ba52a9a14e",
            "upstream_version": "6.1.47",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.1.176",
            "compiled_filter": false
          }
        }
      }
    }
  ],
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-63954"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/010b08084000ef018f1a8de5197087f3b91d8cfe"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/d98d8562b3284b5a5c8eb67e71b794508e46e288"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/1648a3c7f4e18f46a4881920133fc4f2494185a0"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/7c58c55a2a16f7274772507bd1637be609351b4f"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/1d73a533760bc5abb83b3cc759133596f7bb708f"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/0886c6f257fe3663f80218aa1919b0f3f21bf22c"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/4f37bb30b57d6d403d02673074555bd3c3602bef"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/974820a59efde7c1a7e1260bcfe9bb81f833cc9f"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-08-05T13:16:28Z",
    "severity": {
      "source": "kernel CNA",
      "cvss_v3_score": 7.8,
      "cvss_v3_severity": "High",
      "scenario": "AV:L - The bug is reached only through local VFS syscalls (mkdir, create, unlink, rename) on a mounted HPFS filesystem; HPFS is a local block-device filesystem with no network-facing kernel server component.\nAC:L - An attacker can reliably force `hpfs_map_dnode_bitmap()` to fail by mounting a crafted image (e.g. with `check=none` and an invalid `dir_band_bitmap`) or by corrupting the loop/backing device after mount to induce read errors, then triggering a directory operation.\nPR:L - Exploitation requires mounting HPFS (achievable with CAP_SYS_ADMIN inside an unprivileged user namespace) and write access to the mountpoint; it does not require real root in the initial namespace.\nUI:N - In the highest-impact path, the attacker mounts their own malicious HPFS image inside a user namespace and triggers the bug themselves without requiring any victim action such as plugging in media or mounting untrusted storage.\nS:U - Impact is confined to kernel memory management within the same kernel security domain; there is no crossing of VM, container, or IOMMU boundaries.\nC:H - Calling `hpfs_brelse4()` on an uninitialized `quad_buffer_head` performs `kfree()` and `brelse()` on stack garbage, which is uncontrolled memory corruption that can corrupt slab metadata or dereference arbitrary pointers, not a bounded NULL dereference.\nI:H - The erroneous `kfree()`/`brelse()` calls on uninitialized pointers can corrupt kernel heap state and potentially be leveraged for arbitrary writes, matching the guidance to score uncertain memory-corruption bugs at High.\nA:H - The bug reliably causes a kernel oops or panic when `hpfs_map_dnode_bitmap()` fails, resulting in complete loss of system availability for the affected host."
    }
  }
}