CVE-2026-98215 affecting package kernel 6.6.157.1-1

{
  "id": "03d25b3f930781064dc0c09c880ae5480b8aa595c62857cb2f71630babf9d004",
  "url": "https://osv.dev/vulnerability/AZL-106269",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "CVE-2026-98215 affecting package kernel 6.6.157.1-1",
    "summary": "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.",
    "evidence": "osv:AZL-106269",
    "products": [
      {
        "name": {
          "value": "kernel",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "AZL-106269",
      "aliases": [
        "AZL-106269"
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "last_affected": "6.6.157.1-1"
                }
              ]
            }
          ],
          "package": {
            "name": "kernel",
            "purl": "pkg:rpm/azure-linux/kernel",
            "ecosystem": "Azure Linux:3"
          },
          "database_specific": {
            "source": "https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-106269.json"
          }
        }
      ],
      "modified": "2026-10-22T05:35:55Z",
      "provider": "osv",
      "upstream": [
        "CVE-2026-98215"
      ],
      "references": [
        "https://nvd.nist.gov/vuln/detail/CVE-2026-98215"
      ]
    },
    "related_cves": [
      {
        "value": "CVE-2026-98215",
        "evidence": "/upstream"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 404439,
  "published_at": "2026-10-06T09:18:08+00:00"
}