CVE-2026-43405

Technical Description

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

libceph: Use u32 for non-negative values in ceph_monmap_decode()

This patch fixes unnecessary implicit conversions that change signedness

of blob_len and num_mon in ceph_monmap_decode().

Currently blob_len and num_mon are (signed) int variables. They are used

to hold values that are always non-negative and get assigned in

ceph_decode_32_safe(), which is meant to assign u32 values. Both

variables are subsequently used as unsigned values, and the value of

num_mon is further assigned to monmap->num_mon, which is of type u32.

Therefore, both variables should be of type u32. This is especially

relevant for num_mon. If the value read from the incoming message is

very large, it is interpreted as a negative value, and the check for

num_mon > CEPH_MAX_MON does not catch it. This leads to the attempt to

allocate a very large chunk of memory for monmap, which will most likely

fail. In this case, an unnecessary attempt to alloca

Remediation

Check the references section for vendor advisories and patches from linux. Update linux_kernel to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

Affected Products

References