8.1

CVE-2026-109411: Samba: access control bypass via vfs_ceph_rgw case-insensitive open

Awaiting analysis
AliasesDEBIAN-CVE-2026-109411UBUNTU-CVE-2026-109411openSUSE-SU-2026:12334-1
Published 28-10-2026Last modified 30-10-2026

Vulnerability summary

CVE-2026-109411 is a high (CVSS 8.1) Improper Handling of Case Sensitivity vulnerability in samba. EPSS estimates a 0.65% chance of exploitation in the next 30 days, higher than 51.1% of scored vulnerabilities.

Priority
Routine

Not severe (CVSS 8.1, network access); no exploitation reported by the 5 checked sources

Source freshness unavailable

How is this decided?
CVSS score
8.1/10
010
High · v3.1 (CVE.org)
EPSS score
0.65%
0%100%
Low · Change unavailable
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Timeline

  1. 28-10-2026
    PublishedVulnerability first disclosed.
  2. 30-10-2026
    Last modifiedVulnerability information updated.

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.

CVSS metrics

4 scores · 4 sources · 1 version

EPSS trend

Probability

0.65%

Chance of exploitation in the next 30 days

Percentile

51%

Versus all other CVEs

30-day change

Change unavailable

Change unavailable

29-10-202603-11-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Version check

Known conditions: network-reachable, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.

Debian1 product
  • sambaAll versions (No fix recorded) | < 2:4.25.1+dfsg-1
Opensuse1 product
  • samba&distro=openSUSE Tumbleweed< 4.25.1+git.476.bfc358351cb-1.1
Samba1 product
  • samba≥ 4.25.0, < 4.25.1
Ubuntu1 product
  • sambaAll versions (No fix recorded)

4 vendors · 4 products

References

9 links