CVE-2026-43408

HighCVSS 7.8

Published: 08/05/2026(UTC)Updated: 19/10/2026(UTC)Translated: 21/10/2026(UTC)NVD NIST

Exploitation Probability (EPSS)

Low risk

0.18%

7th percentile - higher than 7% of all known CVEs

Summary

In the Linux kernel, the Ceph module has a bug where ceph_path_info structures are not zero-initialized before calling ceph_mdsc_build_path(). On error, ceph_mdsc_free_path_info() may operate on uninitialized data, leading to random kernel crashes (oops, BUG) and potentially allowing privilege escalation.

Risk Assessment

The vulnerability can cause system instability and kernel crashes, and in extreme cases may allow an attacker to escalate privileges. It affects systems with mounted Ceph filesystems.

Recommendation

Update the Linux kernel to a version containing the fix (commit that adds missing initializers for ceph_path_info). If updating is not possible, consider limiting Ceph usage or monitoring for unexpected crashes.

Other vulnerabilities in Linux kernel (Ceph)

CVE-2026-89651Critical
In the Linux kernel, handle_session() in the ceph module lacked bounds checks when decoding the match.path and match.fs_name fields of MDSCapAuth records in a CEPH_SESSION_OPEN message. A malicious or compromised MDS can supply an oversized length, causing an out-of-bounds read (up to 4 GiB) and crashing the client. The fix switches both copies to ceph_decode_copy_safe().

Original NVD description (English source)

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.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS