CVE-2026-23189

Medium

In the Linux kernel, the following vulnerability has been resolved: ceph: fix NULL pointer dereference in ceph_mds_auth_match() The CephFS kernel client has regression starting from 6.18-rc1. We have issue in ceph_mds_auth_match() if fs_name == NULL: const char fs_name = mdsc->fsc->mount_options->mds_namespace; ... if (auth->match.fs_name && strcmp(auth->match.fs_name, fs_name)) { / fsname mismatch, try next one */ return 0; } Patrick Donnelly suggested that: In summary, we should definitely start decoding `fs_name` from the MDSMap and do strict authorizations checks against it. Note that the `-o mds_namespace=foo` should only be used for selecting the file system to mount and nothing else. It's possible no mds_namespace is specified but the kernel will mount the only file system that exists which may have name "foo". This patch reworks ceph_mdsmap_decode() and namespace_equals() with the goal of supporting the suggested concept. Now struct ceph_mdsmap contains m_fs_name field that receives copy of extracted FS name by ceph_extract_encoded_string(). For the case of "old" CephFS file systems, it is used "cephfs" name. [ idryomov: replace redundant %*pE with %s in ceph_mdsmap_decode(), get rid of a series of strlen() calls in ceph_namespace_match(), drop changes to namespace_equals() body to avoid treating empty mds_namespace as equal, drop changes to ceph_mdsc_handle_fsmap() as namespace_equals() isn't an equivalent substitution there ]

Package Linux Kernel
Published 2026-02-14
Last modified 2026-03-18
CVSS version 3.1
Patch available
Yes

CVSS 3.1 score

5.5

out of 10
Medium
Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
High
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Weakness type

CWE-476

CVE-2026-23189 is a NULL Pointer Dereference vulnerability

What is NULL Pointer Dereference?

The product dereferences a pointer that it expects to be valid but is NULL, typically causing a crash. Learn more on MITRE CWE

Affected versions

Linux kernel versions 6.12.58, 6.17.8, 6.18 and later are affected. Fixed in 6.12.70, 6.18.10, 6.19 and their respective stable series.

Affected from
≥ 6.12.58 ≥ 6.17.8 ≥ 6.18
Fixed in
✓ 6.12.70 6.12.x ✓ 6.18.10 6.18.x ✓ 6.19

References

The following references provide additional information about CVE-2026-23189 including vendor advisories, patch commits, exploit details, and third-party analysis. Links are sourced from the NIST NVD database.

Frequently asked questions

  • What is CVE-2026-23189?

    CVE-2026-23189 is a Medium severity Linux kernel vulnerability with a CVSS score of 5.5 out of 10 , classified as a NULL Pointer Dereference flaw (CWE-476) . It affects Linux kernel versions from 6.12.58 onward and has been patched in 6.12.70, 6.18.10 and 6.19. CVE-2026-23189 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

  • What is the CVSS score for CVE-2026-23189?

    CVE-2026-23189 has a CVSS score of 5.5 out of 10, rated Medium severity (CVSS 3.1). The vector string is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H .

  • Is there a patch available for CVE-2026-23189?

    Yes — CVE-2026-23189 has been patched. Fixed versions include 6.12.70, 6.18.10 and 6.19. If you are running Linux kernel 6.12.58 or later up to the fix versions, apply the relevant patch for your kernel branch.

  • Is CVE-2026-23189 actively exploited?

    No — CVE-2026-23189 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.

  • What is NULL Pointer Dereference (CWE-476)?

    The product dereferences a pointer that it expects to be valid but is NULL, typically causing a crash. View CWE-476 on MITRE CWE →

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