{
  "id": "CVE-2026-98215",
  "url": "https://spydr.io/cve/CVE-2026-98215",
  "published": "2026-10-06T09:18:08.107Z",
  "modified": "2026-10-06T09:18:08.107Z",
  "score": null,
  "severity": null,
  "cvss_version": null,
  "vector": null,
  "score_source": null,
  "epss": 0.00209,
  "epss_percentile": 0.10066,
  "exploited": false,
  "kev": null,
  "ssvc_exploitation": null,
  "vendors": [
    "Linux"
  ],
  "products": [
    "Linux"
  ],
  "cwes": [],
  "description": "In the Linux kernel, the following vulnerability has been resolved: selinux: preserve user SID across nested backing files SELinux saves the user file SID in a backing-file security blob so it remains available after mmap() replaces vma->vm_file with a backing file. For nested backing files (overlayfs over overlayfs, or FUSE passthrough backed by overlayfs), user_file may itself be a backing file. Its fsec->sid is the SID of the mounter that opened it, rather than the user that opened the top-level file. mprotect() then checks fd { use } against the mounter SID. This can incorrectly deny access without a domain transition, or check the wrong target SID after one. Copy the saved user SID when user_file is a backing file. Keep using the regular file SID for the first backing layer. With two nested overlayfs mounts and SELinux enforcing, mprotect(PROT_READ) returns EACCES with an fd { use } denial against the mounter SID. With this change, mprotect() succeeds. Tested on arm64 QEMU with a small BusyBox initramfs and a purpose-built SELinux policy. The original test was also repeated with Fedora Cloud Base 44 userspace and gave the same result.",
  "status": "Received",
  "score_type": null,
  "scores": {
    "cvss_v40": null,
    "cvss_v31": null,
    "cvss_v30": null
  },
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/6aaeec59aadcd1eafc18b049f1b759fb6b9d9569",
      "tags": []
    },
    {
      "url": "https://git.kernel.org/stable/c/8c0c602202b9a4909b00bc3354e3c0355bc69e65",
      "tags": []
    },
    {
      "url": "https://git.kernel.org/stable/c/9d99b770e7b67b00bdef9005b928aad13e1d679b",
      "tags": []
    },
    {
      "url": "https://git.kernel.org/stable/c/caa1b913d90d5dc07073733326d2af0f0288f089",
      "tags": []
    },
    {
      "url": "https://git.kernel.org/stable/c/ff20d16b2e8230c034e21540043df47222dcc09b",
      "tags": []
    }
  ],
  "nvd_url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98215",
  "covered_in": [],
  "attribution": [
    {
      "source": "NVD",
      "url": "https://nvd.nist.gov",
      "notice": "This product uses data from the NVD API but is not endorsed or certified by the NVD."
    },
    {
      "source": "CISA KEV",
      "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog",
      "notice": "Known exploited vulnerabilities from the CISA KEV catalog."
    },
    {
      "source": "FIRST EPSS",
      "url": "https://www.first.org/epss",
      "notice": "Exploit prediction scores from FIRST EPSS."
    }
  ]
}