🛡️ CVE-2026-43408 — kernel

🟠 CVSS 7.8 — High ✅ No Known Exploit NVD
7.8
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

ceph: add a bunch of missing ceph_path_info initializers

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.

How this vulnerability can be exploited

This issue can be reached with local access to the system, attack complexity is low, an attacker needs low-level privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality high, integrity high, availability high.

Affected software

CVE-2026-43408 is recorded against 3 packages.

  • kernel (from 6.17.0 up to 6.19.9)
  • linux-kernel
  • unknown

Timeline and source

Published on 8 May 2026 and last revised on 6 August 2026. No public exploit is currently recorded for this entry. A vendor advisory or fix has been published. Record sourced from NVD.

References

git.kernel.org (Web)
git.kernel.org (Web)
git.kernel.org (Web)
git.kernel.org (Web)
github.com (Advisory)
nvd.nist.gov (Advisory)
git.kernel.org (Package)

CVE-2026-43408 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity High
CVSS Score 7.8
CVSS Vector CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CWE N/A
Public Exploit ✅ No
Source NVD
Published 2026-05-08
Updated 2026-08-12
Modified 2026-08-06

Affected Packages

Software From version Fixed in
kernel 6.17.0 6.19.9
linux-kernel — —
unknown — —

Similar Threats

Site Security Check

Is kernel part of your stack?

CVE-2026-43408 is rated CVSS 7.8 High. BotEraser scans your installation against known CVE records and tells you whether this vulnerability applies to the versions you actually run.

Scan My Site Free →

No credit card required  ·  Results in minutes

ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the vulnerabilities listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.