The Linux kernel vulnerability CVE-2026-53167 concerns the FUSE filesystem's handling of FUSE_NOTIFY_RETRIEVE notifications. The flaw arises because FUSE_NOTIFY_RETRIEVE was not restricted to only uptodate folios, potentially allowing uninitialized data from non-uptodate folios to be returned. Since FUSE_NOTIFY_RETRIEVE is intended to return only data already present in the page cache without waiting for data from the FUSE daemon, treating non-uptodate folios as present can expose uninitialized memory. This security impact is limited to systems that do not have automatic zero-initialization of page allocations enabled. The issue is fixed in Linux kernel version 3.0.

The vulnerability can lead to exposure of uninitialized kernel memory data on affected systems, which may impact system availability (as indicated by the CVSS vector's high availability impact). There is no confidentiality or integrity impact reported. The issue only affects systems without automatic zero-initialization of page allocations, limiting the scope of impact.

A fix is available in Linux kernel version 3.0. Systems should be updated to this version or later to remediate the vulnerability. Additionally, enabling automatic zero-initialization of page allocations via CONFIG_INIT_ON_ALLOC_DEFAULT_ON or the kernel parameter init_on_alloc=1 can mitigate the security impact. No known exploits are reported in the wild.