{"cve":"CVE-2021-3996","nvd":{"published":"2022-08-23T20:15:08.560","modified":"2026-06-17T04:06:21.753","status":"Modified","description":"A logic error was found in the libmount library of util-linux in the function that allows an unprivileged user to unmount a FUSE filesystem. This flaw allows a local user on a vulnerable system to unmount other users' filesystems that are either world-writable themselves (like /tmp) or mounted in a world-writable directory. An attacker may use this flaw to cause a denial of service to applications that use the affected filesystems.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":5.5},"cwes":["CWE-552"],"references":["http://packetstormsecurity.com/files/170176/snap-confine-must_mkdir_and_open_with_perms-Race-Condition.html","http://seclists.org/fulldisclosure/2022/Dec/4","http://www.openwall.com/lists/oss-security/2022/11/30/2","https://access.redhat.com/security/cve/CVE-2021-3996","https://bugzilla.redhat.com/show_bug.cgi?id=2024628"],"products":["fedoraproject:fedora","kernel:util-linux"],"source":"nvd","synced_at":"2026-10-19T21:34:18.502168378+00:00"},"epss":{"cve":"CVE-2021-3996","score":0.00641,"percentile":0.50727,"date":"2026-11-01"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}