Vulnerability · Published Oct 28, 2026 · Assigned by redhat
CVE-2026-109411Samba: access control bypass via vfs_ceph_rgw case-insensitive open
High 8.1
In plain English
A high-severity security flaw in Red Hat Enterprise Linux 10 from Red Hat. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 51% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
An access control bypass flaw was identified in Samba's vfs_ceph_rgw module in it's openat() function. An authenticated user can bypass access controls to read or overwrite restricted files on shares configured with the experimental vfs_ceph_rgw module. When a client requests an existing file using mismatched character casing, the module fails to perform a case-insensitive lookup correctly, causing the server to treat the operation as creating a new file. As a result, the server skips standard permission checks on the existing file, allowing the attacker to access or overwrite sensitive data owned by other users.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:14 | samba | 2:4.25.1+dfsg-1 | DEBIAN-CVE-2026-109411 |
| Ubuntu:22.04:LTS | samba | no fix listed | UBUNTU-CVE-2026-109411 |
| Ubuntu:24.04:LTS | samba | no fix listed | UBUNTU-CVE-2026-109411 |
| Ubuntu:26.04:LTS | samba | no fix listed | UBUNTU-CVE-2026-109411 |
| Ubuntu:26.10 | samba | no fix listed | UBUNTU-CVE-2026-109411 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Samba | Samba | 4.25.0 – before 4.25.1 |
| Red Hat | Red Hat Enterprise Linux 10 | see references |
| Red Hat | Red Hat Enterprise Linux 6 | see references |
| Red Hat | Red Hat Enterprise Linux 6 | see references |
| Red Hat | Red Hat Enterprise Linux 7 | see references |
| Red Hat | Red Hat Enterprise Linux 8 | see references |
| Red Hat | Red Hat Enterprise Linux 9 | see references |
| Red Hat | Red Hat OpenShift Container Platform 4 | see references |
| Red Hat | Red Hat OpenShift Container Platform 4 | see references |
| Red Hat | Red Hat OpenShift Container Platform 5 | see references |
Weakness: CWE-178 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
References
- https://access.redhat.com/security/cve/CVE-2026-109411 vdb-entry, x_refsource_REDHAT
- https://attachments.samba.org/attachment.cgi?id=19294
- https://attachments.samba.org/attachment.cgi?id=19295
- RHBZ#2552136 issue-tracking, x_refsource_REDHAT
- https://bugzilla.samba.org/show_bug.cgi?id=16276