CVE-2025-39717 (GCVE-0-2025-39717)
Vulnerability from cvelistv5
Published
2025-09-05 17:21
Modified
2025-09-29 05:58
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: open_tree_attr: do not allow id-mapping changes without OPEN_TREE_CLONE As described in commit 7a54947e727b ('Merge patch series "fs: allow changing idmappings"'), open_tree_attr(2) was necessary in order to allow for a detached mount to be created and have its idmappings changed without the risk of any racing threads operating on it. For this reason, mount_setattr(2) still does not allow for id-mappings to be changed. However, there was a bug in commit 2462651ffa76 ("fs: allow changing idmappings") which allowed users to bypass this restriction by calling open_tree_attr(2) *without* OPEN_TREE_CLONE. can_idmap_mount() prevented this bug from allowing an attached mountpoint's id-mapping from being modified (thanks to an is_anon_ns() check), but this still allows for detached (but visible) mounts to have their be id-mapping changed. This risks the same UAF and locking issues as described in the merge commit, and was likely unintentional.
References
Impacted products
Vendor Product Version
Linux Linux Version: 2462651ffa76b87f9c2e4403ef6e6b89b703fb2f
Version: 2462651ffa76b87f9c2e4403ef6e6b89b703fb2f
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{
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          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nopen_tree_attr: do not allow id-mapping changes without OPEN_TREE_CLONE\n\nAs described in commit 7a54947e727b (\u0027Merge patch series \"fs: allow\nchanging idmappings\"\u0027), open_tree_attr(2) was necessary in order to\nallow for a detached mount to be created and have its idmappings changed\nwithout the risk of any racing threads operating on it. For this reason,\nmount_setattr(2) still does not allow for id-mappings to be changed.\n\nHowever, there was a bug in commit 2462651ffa76 (\"fs: allow changing\nidmappings\") which allowed users to bypass this restriction by calling\nopen_tree_attr(2) *without* OPEN_TREE_CLONE.\n\ncan_idmap_mount() prevented this bug from allowing an attached\nmountpoint\u0027s id-mapping from being modified (thanks to an is_anon_ns()\ncheck), but this still allows for detached (but visible) mounts to have\ntheir be id-mapping changed. This risks the same UAF and locking issues\nas described in the merge commit, and was likely unintentional."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2025-09-29T05:58:02.957Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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      "references": [
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          "url": "https://git.kernel.org/stable/c/69dbdc711d9130136824e3830191a6afffa0a1f0"
        },
        {
          "url": "https://git.kernel.org/stable/c/9308366f062129d52e0ee3f7a019f7dd41db33df"
        }
      ],
      "title": "open_tree_attr: do not allow id-mapping changes without OPEN_TREE_CLONE",
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  "cveMetadata": {
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    "assignerShortName": "Linux",
    "cveId": "CVE-2025-39717",
    "datePublished": "2025-09-05T17:21:24.528Z",
    "dateReserved": "2025-04-16T07:20:57.117Z",
    "dateUpdated": "2025-09-29T05:58:02.957Z",
    "state": "PUBLISHED"
  },
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  }
}


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