CVE-2026-63833 (GCVE-0-2026-63833)

Vulnerability from cvelistv5 – Published: 2026-07-19 12:02 – Updated: 2026-07-20 13:40
VLAI
Title
ntfs3: reject direct userspace writes to reserved $LX* xattrs
Summary
In the Linux kernel, the following vulnerability has been resolved: ntfs3: reject direct userspace writes to reserved $LX* xattrs NTFS3 uses $LXUID, $LXGID, $LXMOD and $LXDEV as internal WSL permission metadata and reloads them into i_uid, i_gid and i_mode from ntfs_get_wsl_perm(). Because the empty-prefix xattr handler also lets file owners call setxattr() on these names directly, an unprivileged writer on a writable ntfs3 mount can plant root ownership and S_ISUID on their own file and gain euid 0 after inode reload. Reject direct userspace writes to the reserved $LX* names. Internal ntfs3 metadata updates are unchanged because ntfs_save_wsl_perm() writes them via ntfs_set_ea() directly. [almaz.alexandrovich@paragon-software.com: added an additional check for non privileged users]
Severity
7.1 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: be71b5cba2e6485e8959da7a9f9a44461a1bb074 , < e574af95234afc3c725988bbc1fdeb46b9f386a4 (git)
Affected: be71b5cba2e6485e8959da7a9f9a44461a1bb074 , < 2c3cd6da4a14380ef79e34bd9dff7caf46687477 (git)
Affected: be71b5cba2e6485e8959da7a9f9a44461a1bb074 , < e8852ae29868e449fdb47eebc28f35fb80741a5f (git)
Affected: be71b5cba2e6485e8959da7a9f9a44461a1bb074 , < f8d420949b335a4b51d06ab276beee6b8dfdc909 (git)
Affected: be71b5cba2e6485e8959da7a9f9a44461a1bb074 , < 5e658b9245a52d838ef93729a7bc07de8e19deb7 (git)
Affected: be71b5cba2e6485e8959da7a9f9a44461a1bb074 , < 293a84fa40b3a1b3471c0545722724bc10973f76 (git)
Affected: be71b5cba2e6485e8959da7a9f9a44461a1bb074 , < 5b08dccecf825cbf905f348bc6ccb497507e28e2 (git)
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Linux Linux Affected: 5.15
Unaffected: 0 , < 5.15 (semver)
Unaffected: 5.15.211 , ≤ 5.15.* (semver)
Unaffected: 6.1.177 , ≤ 6.1.* (semver)
Unaffected: 6.6.144 , ≤ 6.6.* (semver)
Unaffected: 6.12.95 , ≤ 6.12.* (semver)
Unaffected: 6.18.38 , ≤ 6.18.* (semver)
Unaffected: 7.1.3 , ≤ 7.1.* (semver)
Unaffected: 7.2-rc1 , ≤ * (original_commit_for_fix)
Create a notification for this product.
Show details on NVD website
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{
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nntfs3: reject direct userspace writes to reserved $LX* xattrs\n\nNTFS3 uses $LXUID, $LXGID, $LXMOD and $LXDEV as internal WSL\npermission metadata and reloads them into i_uid, i_gid and i_mode\nfrom ntfs_get_wsl_perm().\n\nBecause the empty-prefix xattr handler also lets file owners call\nsetxattr() on these names directly, an unprivileged writer on a\nwritable ntfs3 mount can plant root ownership and S_ISUID on their own\nfile and gain euid 0 after inode reload.\n\nReject direct userspace writes to the reserved $LX* names. Internal\nntfs3 metadata updates are unchanged because ntfs_save_wsl_perm()\nwrites them via ntfs_set_ea() directly.\n\n[almaz.alexandrovich@paragon-software.com: added an additional check for non privileged users]"
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    "cveId": "CVE-2026-63833",
    "datePublished": "2026-07-19T12:02:25.469Z",
    "dateReserved": "2026-07-19T07:54:57.015Z",
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Internal\\nntfs3 metadata updates are unchanged because ntfs_save_wsl_perm()\\nwrites them via ntfs_set_ea() directly.\\n\\n[almaz.alexandrovich@paragon-software.com: added an additional check for non privileged users]\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"fs/ntfs3/xattr.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"be71b5cba2e6485e8959da7a9f9a44461a1bb074\",\"lessThan\":\"e574af95234afc3c725988bbc1fdeb46b9f386a4\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"be71b5cba2e6485e8959da7a9f9a44461a1bb074\",\"lessThan\":\"2c3cd6da4a14380ef79e34bd9dff7caf46687477\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"be71b5cba2e6485e8959da7a9f9a44461a1bb074\",\"lessThan\":\"e8852ae29868e449fdb47eebc28f35fb80741a5f\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"be71b5cba2e6485e8959da7a9f9a44461a1bb074\",\"lessThan\":\"f8d420949b335a4b51d06ab276beee6b8dfdc909\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"be71b5cba2e6485e8959da7a9f9a44461a1bb074\",\"lessThan\":\"5e658b9245a52d838ef93729a7bc07de8e19deb7\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"be71b5cba2e6485e8959da7a9f9a44461a1bb074\",\"lessThan\":\"293a84fa40b3a1b3471c0545722724bc10973f76\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"be71b5cba2e6485e8959da7a9f9a44461a1bb074\",\"lessThan\":\"5b08dccecf825cbf905f348bc6ccb497507e28e2\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"fs/ntfs3/xattr.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"5.15\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"5.15\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"5.15.211\",\"lessThanOrEqual\":\"5.15.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.1.177\",\"lessThanOrEqual\":\"6.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.6.144\",\"lessThanOrEqual\":\"6.6.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.95\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.38\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.1.3\",\"lessThanOrEqual\":\"7.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.2-rc1\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N\",\"baseScore\":7.1,\"baseSeverity\":\"HIGH\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"NONE\"},\"exploitabilityScore\":1.8,\"impactScore\":5.2}]},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/293a84fa40b3a1b3471c0545722724bc10973f76\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/2c3cd6da4a14380ef79e34bd9dff7caf46687477\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/5b08dccecf825cbf905f348bc6ccb497507e28e2\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/5e658b9245a52d838ef93729a7bc07de8e19deb7\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/e574af95234afc3c725988bbc1fdeb46b9f386a4\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/e8852ae29868e449fdb47eebc28f35fb80741a5f\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/f8d420949b335a4b51d06ab276beee6b8dfdc909\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
    "redhat_vex": {
      "aggregate_severity": "None",
      "current_release_date": "2026-07-21T08:07:11+00:00",
      "cve": "CVE-2026-63833",
      "id": "CVE-2026-63833",
      "initial_release_date": "2026-07-19T00:00:00+00:00",
      "product_status:known_not_affected": "1",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: ntfs3: reject direct userspace writes to reserved $LX* xattrs",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-63833.json",
      "version": "3"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.