GCVE Workshop - 22 September 2026 (14:00-18:00), Luxembourg Before The Vulnopticon Conference - Registration

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

Vulnerability from cvelistv5 – Published: 2026-07-19 12:02 – Updated: 2026-08-17 04:51
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 CPE status
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)
guessed Create a notification for this product.
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 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
Show details on NVD website
To clipboard 

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/ntfs3/xattr.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "e574af95234afc3c725988bbc1fdeb46b9f386a4",
              "status": "affected",
              "version": "be71b5cba2e6485e8959da7a9f9a44461a1bb074",
              "versionType": "git"
            },
            {
              "lessThan": "2c3cd6da4a14380ef79e34bd9dff7caf46687477",
              "status": "affected",
              "version": "be71b5cba2e6485e8959da7a9f9a44461a1bb074",
              "versionType": "git"
            },
            {
              "lessThan": "e8852ae29868e449fdb47eebc28f35fb80741a5f",
              "status": "affected",
              "version": "be71b5cba2e6485e8959da7a9f9a44461a1bb074",
              "versionType": "git"
            },
            {
              "lessThan": "f8d420949b335a4b51d06ab276beee6b8dfdc909",
              "status": "affected",
              "version": "be71b5cba2e6485e8959da7a9f9a44461a1bb074",
              "versionType": "git"
            },
            {
              "lessThan": "5e658b9245a52d838ef93729a7bc07de8e19deb7",
              "status": "affected",
              "version": "be71b5cba2e6485e8959da7a9f9a44461a1bb074",
              "versionType": "git"
            },
            {
              "lessThan": "293a84fa40b3a1b3471c0545722724bc10973f76",
              "status": "affected",
              "version": "be71b5cba2e6485e8959da7a9f9a44461a1bb074",
              "versionType": "git"
            },
            {
              "lessThan": "5b08dccecf825cbf905f348bc6ccb497507e28e2",
              "status": "affected",
              "version": "be71b5cba2e6485e8959da7a9f9a44461a1bb074",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/ntfs3/xattr.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.15"
            },
            {
              "lessThan": "5.15",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.211",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.177",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.144",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.95",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.38",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.3",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.15.211",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.177",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.144",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.95",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.38",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1.3",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "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 $LX* names. Internal\nntfs3 metadata updates are unchanged because ntfs_save_wsl_perm()\nwrites them via ntfs_set_ea() directly.\n\n[almaz.alexandrovich@paragon-software.com: added an additional check for non privileged users]"
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.1,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - Exploitation requires the setxattr/fsetxattr syscall against an ntfs3-mounted filesystem; ksmbd and nfsd prefix xattr names with \"user.\" so they cannot reach the empty-prefix \"$LX*\" handler.\nAC:L - An attacker reliably sets the three 4-byte xattrs on a file they own, then forces inode reload via dentry eviction under self-induced memory pressure or umount/remount in a user namespace.\nPR:L - Any unprivileged local user with write access to their own file on a writable ntfs3 mount can trigger the bug; mounting ntfs3 in a user namespace only requires CAP_SYS_ADMIN within that namespace, which counts as Low.\nUI:N - No victim interaction is needed at exploit time; the attacker uses their own local account on an already-mounted writable ntfs3 volume (common on dual-boot/shared NTFS data partitions).\nS:U - Successful exploitation yields host root privileges within the same kernel security domain; it is standard local privilege escalation, not a cross-boundary escape.\nC:H - Planting root ownership and S_ISUID on an executable and executing it after inode reload grants effective UID 0, providing full read access to all kernel-managed data on the system.\nI:H - The bug allows arbitrary tampering with kernel-trusted ownership and permission metadata, culminating in root code execution with unrestricted ability to modify any system data.\nA:N - The vulnerability is a metadata permission bypass with no kernel crash, panic, hang, or denial-of-service component; availability is unaffected by the flaw itself."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T04:51:43.293Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/e574af95234afc3c725988bbc1fdeb46b9f386a4"
        },
        {
          "url": "https://git.kernel.org/stable/c/2c3cd6da4a14380ef79e34bd9dff7caf46687477"
        },
        {
          "url": "https://git.kernel.org/stable/c/e8852ae29868e449fdb47eebc28f35fb80741a5f"
        },
        {
          "url": "https://git.kernel.org/stable/c/f8d420949b335a4b51d06ab276beee6b8dfdc909"
        },
        {
          "url": "https://git.kernel.org/stable/c/5e658b9245a52d838ef93729a7bc07de8e19deb7"
        },
        {
          "url": "https://git.kernel.org/stable/c/293a84fa40b3a1b3471c0545722724bc10973f76"
        },
        {
          "url": "https://git.kernel.org/stable/c/5b08dccecf825cbf905f348bc6ccb497507e28e2"
        }
      ],
      "title": "ntfs3: reject direct userspace writes to reserved $LX* xattrs",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-63833",
    "datePublished": "2026-07-19T12:02:25.469Z",
    "dateReserved": "2026-07-19T07:54:57.015Z",
    "dateUpdated": "2026-08-17T04:51:43.293Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-63833",
      "date": "2026-09-16",
      "epss": "0.00125",
      "percentile": "0.02528"
    },
    "microsoft_vex": {
      "current_release_date": "2026-07-20T14:42:43.000Z",
      "cve": "CVE-2026-63833",
      "id": "msrc_CVE-2026-63833",
      "initial_release_date": "2026-07-20T01:03:29.000Z",
      "product_status:known_affected": "1",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "ntfs3: reject direct userspace writes to reserved $LX* xattrs",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-63833.json",
      "version": "2"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-63833\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-07-19T12:16:56.713\",\"lastModified\":\"2026-08-17T05:17:21.223\",\"vulnStatus\":\"Awaiting Analysis\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"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]\"}],\"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\",\"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": "2026-08-05T14:25:32+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": "275",
      "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"
    },
    "suse_vex": {
      "aggregate_severity": "important",
      "current_release_date": "2026-07-21T13:04:30Z",
      "cve": "CVE-2026-63833",
      "id": "CVE-2026-63833",
      "initial_release_date": "2026-07-19T17:34:31Z",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-63833",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-63833.json",
      "version": "3"
    }
  }
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





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

Author Source Type Date Other

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.


Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.