CVE-2026-63833

Description

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]

References

• https://git.kernel.org/stable/c/293a84fa40b3a1b3471c0545722724bc10973f76
• https://git.kernel.org/stable/c/2c3cd6da4a14380ef79e34bd9dff7caf46687477
• https://git.kernel.org/stable/c/5b08dccecf825cbf905f348bc6ccb497507e28e2
• https://git.kernel.org/stable/c/5e658b9245a52d838ef93729a7bc07de8e19deb7
• https://git.kernel.org/stable/c/e574af95234afc3c725988bbc1fdeb46b9f386a4