CVE-2026-31410

Vulnerability

Overview

A vulnerability was discovered in the ksmbd kernel module, which implements an SMB server in the Linux kernel. The issue lies in the handling of the FS_OBJECT_ID_INFORMATION request, where the server was not using the proper volume UUID. Instead of relying on the filesystem's unique identifier (sb->s_uuid), the code could fall back to an incorrect or inconsistent value, potentially leading to misidentification of the volume [1].

Exploitation and

Attack Surface

This vulnerability is triggered when an SMB client requests object ID information from a share served by ksmbd. An attacker with network access to the SMB share could potentially exploit this to obtain inconsistent or incorrect volume identifiers. No authentication is required beyond normal SMB access, but the attacker must be able to send crafted SMB requests to the server [2].

Impact

By returning a non-unique or incorrect volume UUID, the vulnerability could allow an attacker to confuse client applications that rely on volume identity for caching or synchronization purposes. In worst-case scenarios, this could lead to data integrity issues or information disclosure, though the CVSS score of 5.5 (Medium) indicates limited direct impact [3].

Mitigation

The fix has been applied to the Linux kernel stable branches via commits that change the logic to first use sb->s_uuid from the underlying filesystem, and only fall back to the statfs f_fsid value when no UUID is available [4]. Users are advised to update their kernels to the latest stable release to receive the patch.