CVE-2026-63833

Public on 2026-07-19
Modified on 2026-07-24
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]
Severity
Important severity
Important
See what this means
CVSS v3 Base Score
7.8
See breakdown

Affected Packages

Platform Package Release Date Advisory Status
Amazon Linux 2 - Kernel-5.15 Extra kernel 2026-07-27 ALAS2KERNEL-5.15-2026-111 Fixed
Amazon Linux 2 - Core kernel Not Affected
Amazon Linux 2 - Kernel-5.10 Extra kernel Not Affected
Amazon Linux 2 - Kernel-5.4 Extra kernel Not Affected
Amazon Linux 2023 kernel 2026-08-04 ALAS2023-2026-2032 Fixed
Amazon Linux 2023 kernel6.12 2026-08-04 ALAS2023-2026-2014 Fixed
Amazon Linux 2023 kernel6.18 2026-07-20 ALAS2023-2026-1969 Fixed

CVSS Scores

Score Type Score Vector
Amazon Linux CVSSv3 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H