{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-63833", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-07-19T07:54:57.015Z", "datePublished": "2026-07-19T12:02:25.469Z", "dateUpdated": "2026-08-17T04:51:43.293Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-17T04:51:43.293Z" }, "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 $LX* names. Internal\nntfs3 metadata updates are unchanged because ntfs_save_wsl_perm()\nwrites them via ntfs_set_ea() directly.\n\n[almaz.alexandrovich@paragon-software.com: added an additional check for non privileged users]" } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N", "baseScore": 7.1, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - Exploitation requires the setxattr/fsetxattr syscall against an ntfs3-mounted filesystem; ksmbd and nfsd prefix xattr names with \"user.\" so they cannot reach the empty-prefix \"$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." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/ntfs3/xattr.c" ], "versions": [ { "version": "be71b5cba2e6485e8959da7a9f9a44461a1bb074", "lessThan": "e574af95234afc3c725988bbc1fdeb46b9f386a4", "status": "affected", "versionType": "git" }, { "version": "be71b5cba2e6485e8959da7a9f9a44461a1bb074", "lessThan": "2c3cd6da4a14380ef79e34bd9dff7caf46687477", "status": "affected", "versionType": "git" }, { "version": "be71b5cba2e6485e8959da7a9f9a44461a1bb074", "lessThan": "e8852ae29868e449fdb47eebc28f35fb80741a5f", "status": "affected", "versionType": "git" }, { "version": "be71b5cba2e6485e8959da7a9f9a44461a1bb074", "lessThan": "f8d420949b335a4b51d06ab276beee6b8dfdc909", "status": "affected", "versionType": "git" }, { "version": "be71b5cba2e6485e8959da7a9f9a44461a1bb074", "lessThan": "5e658b9245a52d838ef93729a7bc07de8e19deb7", "status": "affected", "versionType": "git" }, { "version": "be71b5cba2e6485e8959da7a9f9a44461a1bb074", "lessThan": "293a84fa40b3a1b3471c0545722724bc10973f76", "status": "affected", "versionType": "git" }, { "version": "be71b5cba2e6485e8959da7a9f9a44461a1bb074", "lessThan": "5b08dccecf825cbf905f348bc6ccb497507e28e2", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/ntfs3/xattr.c" ], "versions": [ { "version": "5.15", "status": "affected" }, { "version": "0", "lessThan": "5.15", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.211", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.177", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.144", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.95", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.38", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1.3", "lessThanOrEqual": "7.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15", "versionEndExcluding": "5.15.211" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15", "versionEndExcluding": "6.1.177" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15", "versionEndExcluding": "6.6.144" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15", "versionEndExcluding": "6.12.95" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15", "versionEndExcluding": "6.18.38" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15", "versionEndExcluding": "7.1.3" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15", "versionEndExcluding": "7.2" } ] } ] } ], "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" } } } }