{"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"}}}}