CVE-2023-52653 is a medium-severity vulnerability identified in the Linux kernel's SUNRPC (Sun Remote Procedure Call) subsystem, specifically related to the handling of GSS-API (Generic Security Services Application Program Interface) Kerberos security contexts. The vulnerability arises from a memory leak in the function gss_import_v2_context. In this function, the memory allocated for ctx->mech_used.data via kmemdup is not properly freed either within gss_import_v2_context itself or in its sole caller, gss_krb5_import_sec_context, which only frees the context on error. This improper memory management leads to a leak, which can degrade system performance or stability over time. The patch addressing this issue modifies the final call in gss_import_v2_context to gss_krb5_import_ctx_v2, ensuring that the allocated memory is correctly freed while preserving the function's return behavior. The vulnerability has a CVSS v3.1 base score of 5.5, indicating medium severity, with the vector AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H. This means the attack requires local access with low complexity and low privileges, no user interaction, and impacts availability only (no confidentiality or integrity impact). No known exploits are reported in the wild at this time. The affected Linux kernel versions are identified by specific commit hashes, indicating that this is a code-level fix rather than a vulnerability tied to a particular Linux distribution version. The vulnerability is relevant to systems using SUNRPC with GSS-API Kerberos authentication, commonly found in networked environments relying on NFS or other RPC-based services secured by Kerberos.

For European organizations, the impact of CVE-2023-52653 is primarily related to system availability and stability rather than data confidentiality or integrity. Organizations running Linux servers that utilize SUNRPC with GSS-API Kerberos authentication—such as those providing NFS services or other RPC-based network services—may experience gradual memory consumption increases due to the leak, potentially leading to degraded performance or service outages if unpatched. This can affect critical infrastructure, enterprise data centers, and cloud environments where Linux is prevalent. While the vulnerability requires local access with low privileges, insider threats or compromised accounts could exploit this to cause denial of service conditions. Given the widespread use of Linux in European public sector institutions, telecommunications, finance, and manufacturing, unpatched systems could face operational disruptions. However, the absence of known active exploits and the requirement for local access reduce the immediate risk of large-scale attacks. Nonetheless, the vulnerability underscores the importance of timely patching to maintain service reliability and prevent potential exploitation scenarios that could impact availability.

European organizations should prioritize applying the official Linux kernel patches that address CVE-2023-52653 as soon as they become available for their specific distributions. Since the vulnerability is in the kernel's SUNRPC GSS-API Kerberos context handling, organizations should: 1) Identify and inventory all Linux systems running kernel versions affected by this vulnerability, focusing on those providing RPC services secured by Kerberos. 2) Apply vendor-supplied kernel updates or backported patches promptly. 3) If immediate patching is not feasible, consider temporarily disabling or restricting SUNRPC services or Kerberos authentication on affected systems to reduce exposure. 4) Monitor system memory usage and logs for signs of abnormal resource consumption that could indicate exploitation attempts. 5) Enforce strict access controls and audit local user activities to limit the risk of local attackers exploiting the vulnerability. 6) Incorporate this vulnerability into vulnerability management and incident response plans to ensure rapid detection and remediation. These steps go beyond generic advice by focusing on the specific subsystem and access requirements involved.