Bug 2449771 (CVE-2026-33150)

Summary: CVE-2026-33150 libfuse: libfuse: Arbitrary code execution via use-after-free in io_uring subsystem
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedKeywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in libfuse. A use-after-free vulnerability in the io_uring subsystem allows a local attacker to potentially execute arbitrary code and crash FUSE (Filesystem in Userspace) filesystem processes. This occurs when io_uring thread creation fails due to resource exhaustion, such as limits imposed by cgroup pids.max, causing a dangling pointer to be stored and later used during session shutdown. This vulnerability is reliably triggered in containerized environments.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Bug Depends On: 2451602, 2451603, 2451604, 2451605    
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Description OSIDB Bzimport 2026-03-20 21:01:44 UTC 
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.