FUSE-uring Use-After-Free from Premature Request Commitment

CVE-2026-64259 is a use-after-free vulnerability in the Linux kernel's FUSE-uring subsystem that allows malicious userspace applications to trigger memory safety violations. The vulnerability exists in the interaction between io_uring commit operations and FUSE request handling, where a compromised or malicious userspace process can submit commit SQEs (Submission Queue Entries) with request IDs that reference FUSE requests not yet sent to the server. This affects systems running vulnerable Linux kernels where io_uring is exposed to untrusted userspace, particularly in containerized environments, cloud platforms, and multi-tenant systems where kernel interfaces are accessible to potentially hostile applications.

Casky's security skills mapped to MITRE ATT&CK would detect exploitation patterns associated with T1055 (Process Injection) and T1203 (Exploitation for Privilege Escalation) through behavioral analysis of io_uring command submission anomalies and memory corruption indicators. Practitioners using Casky would observe findings highlighting suspicious patterns: premature ring entry state transitions, memcpy operations on uninitialized or freed memory regions, and kernel crash signatures consistent with use-after-free conditions. The platform's extended reasoning capabilities would correlate SQE commit timing violations with kernel heap corruptions, allowing security teams to identify when userspace is attempting to manipulate FUSE request lifecycle management outside normal operational boundaries—a critical detection point for privilege escalation attempts leveraging kernel memory vulnerabilities.