CVE-2024-44947 is a vulnerability identified in the Linux kernel's FUSE (Filesystem in Userspace) implementation. The issue arises from improper initialization of page contents beyond the end-of-file (EOF) in the fuse_notify_store() function. Unlike fuse_do_readpage(), fuse_notify_store() does not enable page zeroing, which is necessary to ensure that all parts of a page, including those beyond EOF, are fully initialized before marking the page as up-to-date. This flaw can result in uninitialized memory contents being exposed to userspace processes through mmap() operations. Essentially, this is an information leak vulnerability where sensitive kernel memory or residual data from previous allocations could be inadvertently disclosed to unprivileged userspace applications. The vulnerability specifically affects Linux systems that do not have the kernel configuration option CONFIG_INIT_ON_ALLOC_DEFAULT_ON enabled or the equivalent kernel command line parameter set. This option ensures that memory pages are zero-initialized upon allocation, mitigating the risk of leaking stale data. Since the vulnerability is related to the FUSE subsystem, it impacts systems that use FUSE filesystems, which are common for mounting user-space filesystems such as SSHFS, NTFS-3G, or custom filesystems. The vulnerability does not require authentication or user interaction beyond normal filesystem access, and no known exploits are currently reported in the wild. However, the exposure of uninitialized memory can potentially reveal sensitive information, which could be leveraged in further attacks or privilege escalation chains.

For European organizations, the impact of CVE-2024-44947 centers on confidentiality breaches due to information leakage. Organizations running Linux servers or workstations with FUSE filesystems and without the init-on-alloc memory zeroing enabled are at risk. This includes cloud service providers, hosting companies, enterprises using Linux-based infrastructure, and developers relying on FUSE for custom filesystem implementations. The leaked data could include fragments of sensitive information from kernel memory or other userspace processes, potentially exposing credentials, cryptographic keys, or proprietary data. While the vulnerability does not directly enable code execution or denial of service, the information leak could facilitate targeted attacks or lateral movement within networks. Given the widespread use of Linux in European critical infrastructure, financial institutions, and government agencies, the vulnerability poses a moderate risk especially if combined with other vulnerabilities. The lack of known exploits reduces immediate risk, but the vulnerability should be addressed promptly to prevent future exploitation.

To mitigate CVE-2024-44947, European organizations should: 1) Apply the latest Linux kernel patches that address this vulnerability as soon as they become available. 2) Enable the CONFIG_INIT_ON_ALLOC_DEFAULT_ON kernel configuration option or set the equivalent kernel command line parameter to ensure memory pages are zero-initialized on allocation, preventing uninitialized memory exposure. 3) Audit systems to identify usage of FUSE filesystems and assess whether they are running vulnerable kernel versions without init-on-alloc enabled. 4) Limit access to FUSE-mounted filesystems to trusted users and processes to reduce the risk of unauthorized information disclosure. 5) Monitor system logs and filesystem activity for unusual mmap() operations or suspicious access patterns that could indicate attempts to exploit this vulnerability. 6) Incorporate this vulnerability into vulnerability management and patching workflows to ensure timely remediation. 7) For high-security environments, consider disabling FUSE if not required or isolating FUSE usage within containerized or sandboxed environments to limit potential impact.