Description
libfuse is the reference implementation of the Linux FUSE. From version 3.18.0 to before version 3.18.2, a use-after-free vulnerability in the io_uring subsystem of libfuse allows a local attacker to crash FUSE filesystem processes and potentially execute arbitrary code. When io_uring thread creation fails due to resource exhaustion (e.g., cgroup pids.max), fuse_uring_start() frees the ring pool structure but stores the dangling pointer in the session state, leading to a use-after-free when the session shuts down. The trigger is reliable in containerized environments where cgroup pids.max limits naturally constrain thread creation. This issue has been patched in version 3.18.2.
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References
github.com/...ibfuse/security/advisories/GHSA-qxv7-xrc2-qmfx
github.com/...ommit/49fcd891a58f622c098e2ca67d66086f7b213836
github.com/libfuse/libfuse/releases/tag/fuse-3.18.2