CVE-2021-3995

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 an unprivileged local attacker to unmount FUSE filesystems that belong to certain other users who have a UID that is a prefix of the UID of the attacker in its string form. An attacker may use this flaw to cause a denial of service to applications that use the affected filesystems.

Database specific

{
    "unresolved_ranges": [
        {
            "source": "CPE_FIELD",
            "extracted_events": [
                {
                    "last_affected": "35"
                }
            ],
            "cpe": "cpe:2.3:o:fedoraproject:fedora:35:*:*:*:*:*:*:*"
        }
    ]
}

References

Affected packages

Git / github.com/util-linux/util-linux

Affected ranges

Type

GIT

Repo

https://github.com/util-linux/util-linux

Events

Introduced

d4319b91c9d7d69e7b954fc66819214f81501312

Fixed

331a1e6e10f7943a12112c7161a8c995c1c5b9b9

Fixed

57202f5713afa2af20ffbb6ab5331481d0396f8d

Database specific

{
    "source": [
        "CPE_FIELD",
        "REFERENCES"
    ],
    "extracted_events": [
        {
            "introduced": "2.34"
        },
        {
            "fixed": "2.37.3"
        }
    ],
    "cpe": "cpe:2.3:a:kernel:util-linux:*:*:*:*:*:*:*:*"
}

Affected versions

v2.*

v2.34

v2.35

v2.35-rc1

v2.35-rc2

v2.36

v2.36-rc1

v2.36-rc2

v2.37

v2.37-rc1

v2.37-rc2

v2.37.1

v2.37.2

Database specific

vanir_signatures_modified

"2026-04-12T01:58:36Z"

vanir_signatures

[
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        "source": "https://github.com/util-linux/util-linux/commit/57202f5713afa2af20ffbb6ab5331481d0396f8d",
        "signature_version": "v1",
        "id": "CVE-2021-3995-1269fc08",
        "deprecated": false,
        "target": {
            "file": "libmount/src/context_umount.c"
        },
        "digest": {
            "threshold": 0.9,
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        "signature_type": "Line",
        "source": "https://github.com/util-linux/util-linux/commit/57202f5713afa2af20ffbb6ab5331481d0396f8d",
        "signature_version": "v1",
        "id": "CVE-2021-3995-2ca3bb48",
        "deprecated": false,
        "target": {
            "file": "libmount/src/mountP.h"
        },
        "digest": {
            "threshold": 0.9,
            "line_hashes": [
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    },
    {
        "signature_type": "Function",
        "deprecated": false,
        "signature_version": "v1",
        "id": "CVE-2021-3995-74f6c434",
        "source": "https://github.com/util-linux/util-linux/commit/57202f5713afa2af20ffbb6ab5331481d0396f8d",
        "digest": {
            "length": 908.0,
            "function_hash": "109824080416446340833412381312032531836"
        },
        "target": {
            "file": "libmount/src/context_umount.c",
            "function": "is_fuse_usermount"
        }
    },
    {
        "signature_type": "Line",
        "deprecated": false,
        "signature_version": "v1",
        "id": "CVE-2021-3995-a6de3fc7",
        "source": "https://github.com/util-linux/util-linux/commit/57202f5713afa2af20ffbb6ab5331481d0396f8d",
        "target": {
            "file": "libmount/src/optstr.c"
        },
        "digest": {
            "threshold": 0.9,
            "line_hashes": [
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        }
    }
]

source

"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2021-3995.json"