{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2026-43403",
  "modified": "2026-10-09T11:39:44Z",
  "upstream": [
    "CVE-2026-43403"
  ],
  "published": "2026-05-08T14:22:57Z",
  "summary": "nsfs: tighten permission checks for ns iteration ioctls",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnsfs: tighten permission checks for ns iteration ioctls\n\nEven privileged services should not necessarily be able to see other\nprivileged service's namespaces so they can't leak information to each\nother. Use may_see_all_namespaces() helper that centralizes this policy\nuntil the nstree adapts.",
  "severity": [
    {
      "type": "CVSS_V3",
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H"
    }
  ],
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  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-43403"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/3376b345df155ca36d8611857b41ff7d5183fc38"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/2f3dea284c761c890d676f77d5e55c0c496b4ef4"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/0ad650e60150eda789deca5e78a6a09d26bf8fc9"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/e6b899f08066e744f89df16ceb782e06868bd148"
    }
  ],
  "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": 8.8,
      "cvss_v3_severity": "High",
      "scenario": "AV:L - The vulnerable path is reached by a local `ioctl()` on an nsfs mount-namespace file descriptor, such as one obtained from `/proc/self/ns/mnt` or pidfd namespace ioctls. There is no network, adjacent, or physical attack path.\nAC:L - Triggering is deterministic: open a mount namespace fd and issue `NS_MNT_GET_NEXT` or `NS_MNT_GET_PREV`. There is no race or special memory-layout condition required.\nPR:L - The pre-fix check only required `CAP_SYS_ADMIN` in the target mount namespace's owning user namespace, which can be satisfied through user namespaces in plausible deployments. Under the higher-severity rule, this is Low rather than High.\nUI:N - No victim interaction is needed once the attacker has local execution and the relevant namespace capability. The attacker directly invokes the ioctl.\nS:C - The bug lets one namespace-confined service obtain file descriptors for other mount namespaces, bypassing the intended namespace visibility boundary. That can cross container or service isolation boundaries.\nC:H - The returned namespace fd and mount namespace id allow enumeration with `listmount()` and `statmount()`, exposing mount topology, paths, sources, options, and related metadata from another namespace. In plausible privileged-container scenarios, the fd can also enable `setns()` into the target mount namespace and expose sensitive filesystem contents.\nI:H - With the leaked mount namespace fd and the same namespace capabilities required by the vulnerable path, an attacker can plausibly `setns()` into another mount namespace and modify writable files or mount state there. This can compromise integrity across the namespace boundary.\nA:H - After obtaining and entering another mount namespace in a privileged scenario, the attacker can disrupt that namespace by altering or unmounting resources or damaging writable files. This can cause high availability impact to the affected service or container."
    }
  }
}