# CVE-2026-109411: Samba access control bypass in vfs_ceph_rgw

Source: https://junglewise.ai/threats/cve-2026-109411-an-access-control-bypass-flaw-was-found-in-samba-s-vfs-ceph-rgw  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-28. Updated: 2026-10-28  
License: CC BY 4.0 with a link back

CVE-2026-109411 · Severity: high · CVSS 8.1 · Published 2026-10-28

Samba is a file and print server that enables interoperability between Linux and Windows systems. An authenticated user can bypass access controls in shares using the experimental vfs_ceph_rgw module to read or overwrite files belonging to other users by exploiting a case-sensitivity bug in file lookup logic.

Technologies: [Samba](https://junglewise.ai/threats/technologies/samba). Vendors: [Samba](https://junglewise.ai/threats/vendors/samba).

## Quick answers

**Is CVE-2026-109411 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-109411 being exploited in the wild.

**How severe is CVE-2026-109411?** High severity, with a CVSS score of 8.1, published 28 October 2026.

**Which products and versions are affected?** Samba Samba.

**Is there a fix for CVE-2026-109411?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-109411 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-109411?** Check whether you run Samba. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The vfs_ceph_rgw module's openat() function fails to perform case-insensitive filename lookups correctly. When an authenticated client requests an existing file with mismatched character casing, the module incorrectly treats the operation as file creation rather than file access, causing the server to skip standard permission checks and allowing access or modification of files owned by other users.

## Affected products

- Samba Samba

## Timeline

- 2026-10-28: disclosed

## References

- [https://gitlab.com/samba-team/samba](https://gitlab.com/samba-team/samba)
- [https://access.redhat.com/downloads/content/package-browser/](https://access.redhat.com/downloads/content/package-browser/)

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