Description
In the Linux kernel, the following vulnerability has been resolved:

ceph: add a bunch of missing ceph_path_info initializers

ceph_mdsc_build_path() must be called with a zero-initialized
ceph_path_info parameter, or else the following
ceph_mdsc_free_path_info() may crash.

Example crash (on Linux 6.18.12):

virt_to_cache: Object is not a Slab page!
WARNING: CPU: 184 PID: 2871736 at mm/slub.c:6732 kmem_cache_free+0x316/0x400
[...]
Call Trace:
[...]
ceph_open+0x13d/0x3e0
do_dentry_open+0x134/0x480
vfs_open+0x2a/0xe0
path_openat+0x9a3/0x1160
[...]
cache_from_obj: Wrong slab cache. names_cache but object is from ceph_inode_info
WARNING: CPU: 184 PID: 2871736 at mm/slub.c:6746 kmem_cache_free+0x2dd/0x400
[...]
kernel BUG at mm/slub.c:634!
Oops: invalid opcode: 0000 [#1] SMP NOPTI
RIP: 0010:__slab_free+0x1a4/0x350

Some of the ceph_mdsc_build_path() callers had initializers, but
others had not, even though they were all added by commit 15f519e9f883
("ceph: fix race condition validating r_parent before applying state").
The ones without initializer are suspectible to random crashes. (I can
imagine it could even be possible to exploit this bug to elevate
privileges.)

Unfortunately, these Ceph functions are undocumented and its semantics
can only be derived from the code. I see that ceph_mdsc_build_path()
initializes the structure only on success, but not on error.

Calling ceph_mdsc_free_path_info() after a failed
ceph_mdsc_build_path() call does not even make sense, but that's what
all callers do, and for it to be safe, the structure must be
zero-initialized. The least intrusive approach to fix this is
therefore to add initializers everywhere.
Published: 2026-05-08
Score: 7.0 High
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

Impact

The Linux kernel bug originates when the ceph_mdsc_build_path() function fails to zero‑initialize a ceph_path_info structure that is later freed by ceph_mdsc_free_path_info(). Because the structure can contain garbage values, the free routine may access an incorrect slab cache, provoking a kernel BUG and an infamous oops. The crash can be triggered by any operation that exercises Ceph path resolution, and the author notes that an attacker could potentially exploit this defect to gain elevated privileges. The vulnerability is an uninitialized‑variable flaw that can lead to memory corruption and a use‑after‑free scenario.

Affected Systems

The issue is confined to the Linux kernel's Ceph integration. The example crash was observed on kernel 6.18.12 and the flaw was introduced by commit 15f519e9f883. All kernel releases that incorporate that commit without the missing initializers are affected, while any release that applies the subsequent patch to add the initializers fixes the problem. No vendor‑specific product list beyond the Linux kernel is available.

Risk and Exploitability

The EPSS score is not available, the KEV flag indicates the vulnerability is not listed in CISA KEV, and the CVSS score of 7.0 indicates a high severity. Exploitation would require triggering the buggy Ceph code path, which is likely a local or remote vector depending on the Ceph client configuration. Prompt patching or mitigation is strongly recommended.

Generated by OpenCVE AI on May 9, 2026 at 04:41 UTC.

Remediation

No vendor fix or workaround currently provided.

OpenCVE Recommended Actions

  • Apply the Linux kernel update that contains the fix for missing ceph_path_info initializers (commit 15f519e9f883 or later).
  • If a kernel update is not immediately available, backport the missing initializers patch to your current kernel source tree and rebuild the kernel modules.
  • Limit exposure by disabling Ceph features that invoke ceph_mdsc_build_path() on untrusted hosts or by restricting kernel access to trusted users only.
  • Monitor system logs for “kernel BUG” or “slub” messages, and schedule an urgent kernel reboot if a crash occurs before the patch can be applied.

Generated by OpenCVE AI on May 9, 2026 at 04:41 UTC.

Tracking

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Advisories

No advisories yet.

History

Sat, 09 May 2026 03:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-416
CWE-457

Sat, 09 May 2026 00:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-908
References
Metrics threat_severity

None

cvssV3_1

{'score': 7.0, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'}

threat_severity

Moderate


Fri, 08 May 2026 19:30:00 +0000

Type Values Removed Values Added
Weaknesses CWE-416
CWE-457

Fri, 08 May 2026 14:45:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: ceph: add a bunch of missing ceph_path_info initializers ceph_mdsc_build_path() must be called with a zero-initialized ceph_path_info parameter, or else the following ceph_mdsc_free_path_info() may crash. Example crash (on Linux 6.18.12): virt_to_cache: Object is not a Slab page! WARNING: CPU: 184 PID: 2871736 at mm/slub.c:6732 kmem_cache_free+0x316/0x400 [...] Call Trace: [...] ceph_open+0x13d/0x3e0 do_dentry_open+0x134/0x480 vfs_open+0x2a/0xe0 path_openat+0x9a3/0x1160 [...] cache_from_obj: Wrong slab cache. names_cache but object is from ceph_inode_info WARNING: CPU: 184 PID: 2871736 at mm/slub.c:6746 kmem_cache_free+0x2dd/0x400 [...] kernel BUG at mm/slub.c:634! Oops: invalid opcode: 0000 [#1] SMP NOPTI RIP: 0010:__slab_free+0x1a4/0x350 Some of the ceph_mdsc_build_path() callers had initializers, but others had not, even though they were all added by commit 15f519e9f883 ("ceph: fix race condition validating r_parent before applying state"). The ones without initializer are suspectible to random crashes. (I can imagine it could even be possible to exploit this bug to elevate privileges.) Unfortunately, these Ceph functions are undocumented and its semantics can only be derived from the code. I see that ceph_mdsc_build_path() initializes the structure only on success, but not on error. Calling ceph_mdsc_free_path_info() after a failed ceph_mdsc_build_path() call does not even make sense, but that's what all callers do, and for it to be safe, the structure must be zero-initialized. The least intrusive approach to fix this is therefore to add initializers everywhere.
Title ceph: add a bunch of missing ceph_path_info initializers
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References

Subscriptions

Linux Linux Kernel
cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-05-08T14:21:47.579Z

Reserved: 2026-05-01T14:12:56.008Z

Link: CVE-2026-43408

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-05-08T15:16:52.397

Modified: 2026-05-08T15:16:52.397

Link: CVE-2026-43408

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-05-08T00:00:00Z

Links: CVE-2026-43408 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-05-09T04:45:26Z

Weaknesses