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Vulnerability · Published Mar 20, 2026 · Assigned by GitHub_M

CVE-2026-33150Use After Free in libfuse

High 7.8

In plain English

A high-severity use-after-free in libfuse from libfuse. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 25% of all known vulnerabilities). Ready-made attack tooling exists: public proof-of-concept code. Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.8High
Exploit odds (30 days)0.3%top 74.7% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack tooling1Public PoC

Official 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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:14fuse33.18.2-1DEBIAN-CVE-2026-33150
Ubuntu:26.04:LTSfuse3no fix listedUBUNTU-CVE-2026-33150

Affected products (as reported)

VendorProductVersions
libfuse libfuse >= 3.18.0, < 3.18.2

Weakness: CWE-416, CWE-825 · Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

References