CVE-2026-63833

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 iuid, igid and imode from ntfsgetwslperm().

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 ntfssavewslperm() writes them via ntfsset_ea() directly.

[almaz.alexandrovich@paragon-software.com: added an additional check for non privileged users]