The vulnerability CVE-2026-1933 affects Samba's handling of NTFS-style reparse points on shares configured with 'read only = yes'. Because of missing access checks at the SMB protocol layer, authenticated users who have write permissions on the underlying filesystem can create or delete reparse point metadata via SMB operations even on read-only exports. This improper access control could allow modification of SMB-visible file behavior, including converting files into symbolic links or other reparse point types. Red Hat has issued a critical security advisory and released patches for Samba on Red Hat Enterprise Linux 10 to fix this issue.

The vulnerability allows authenticated users with write access to the underlying filesystem to bypass SMB-layer access controls on read-only shares, potentially modifying file behavior visible over SMB. This could lead to unauthorized changes such as creating symbolic links or other reparse point types, which may impact system integrity and availability. The CVSS v3.1 base score is 7.1 (High), with impact primarily on integrity and availability but no confidentiality impact.

Red Hat has released official security updates for Samba on Red Hat Enterprise Linux 10 that address CVE-2026-1933 by adding the missing access checks on reparse point operations. Users should apply the updated Samba packages as provided in Red Hat Security Advisory RHSA-2026:22963 or later. Detailed update instructions are available at https://access.redhat.com/articles/11258. Applying these updates fully mitigates the vulnerability.