{
    "dataType": "CVE_RECORD",
    "dataVersion": "5.2",
    "cveMetadata": {
        "cveId": "CVE-2026-98983",
        "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "state": "PUBLISHED",
        "assignerShortName": "Linux",
        "dateReserved": "2026-09-25T10:25:14.384Z",
        "datePublished": "2026-10-23T12:20:00.918Z",
        "dateUpdated": "2026-10-23T12:20:00.918Z"
    },
    "containers": {
        "cna": {
            "providerMetadata": {
                "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
                "shortName": "Linux",
                "dateUpdated": "2026-10-23T12:20:00.918Z"
            },
            "descriptions": [
                {
                    "lang": "en",
                    "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nunshare: don't drop active namespace references that were never taken\n\nActive references on the namespaces of an nsproxy are taken when the\nnsproxy is installed into a task in switch_task_namespaces() and\ncopy_namespaces() and dropped again by put_nsproxy() through\ndeactivate_nsproxy().\n\nBut ksys_unshare() calls put_nsproxy() on an nsproxy that was never\ninstalled when set_cred_ucounts() fails. The new namespaces of that\nnsproxy go from zero to minus one and the namespaces shared with the\ncaller lose a reference that belongs to the nsproxy the caller keeps\nusing:\n\n  WARNING: kernel/nscommon.c:171 at __ns_ref_active_put+0x1cd/0x230\n   nsproxy_ns_active_put\n   deactivate_nsproxy\n   ksys_unshare\n\nAfterwards the namespaces the caller lives in aren't listed by listns()\nanymore. set_cred_ucounts() only fails when alloc_ucounts() can't\nallocate and it only allocates when the real uid of the caller differs\nfrom its effective uid.\n\nCommit cefd55bd2159 (\"nsproxy: fix free_nsproxy() and simplify\ncreate_new_namespaces()\") separated the two cases on purpose.\nnsproxy_free() frees an nsproxy that was prepared but never installed\nand that's what a failed setns() uses in put_nsset(). Export it and use\nit for a failed unshare() as well."
                }
            ],
            "affected": [
                {
                    "product": "Linux",
                    "vendor": "Linux",
                    "defaultStatus": "unaffected",
                    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                    "programFiles": [
                        "include/linux/nsproxy.h",
                        "kernel/fork.c",
                        "kernel/nsproxy.c"
                    ],
                    "versions": [
                        {
                            "version": "a98621a0f187a934c115dcfe79a49520ae892111",
                            "lessThan": "56fe03a0c05dba4c5f6a23c391f96de1614a098c",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "a98621a0f187a934c115dcfe79a49520ae892111",
                            "lessThan": "0b6f31a3c0b16066f812e94b52a704174a6f23cd",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "27ae6b17c9ba7ff353ab0906297f08aa845782b4",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "297261b343371c4f0b31055d53d285138ec21565",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "813a47b0309097da71781ee4ac11922e39b67d55",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "6e608e3e5ce12ce7fd21e46212eccca37f917d0e",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "a261fccdb4ac58ec5ba6aa1d92a6cc418fff301f",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "665dc1ed16357988d439fc5bbc860ee36f540d81",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "5.15.209",
                            "lessThan": "5.16",
                            "status": "affected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.1.175",
                            "lessThan": "6.2",
                            "status": "affected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.6.141",
                            "lessThan": "6.7",
                            "status": "affected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.12.91",
                            "lessThan": "6.13",
                            "status": "affected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.18.33",
                            "lessThan": "6.19",
                            "status": "affected",
                            "versionType": "semver"
                        },
                        {
                            "version": "7.0.10",
                            "lessThan": "7.1",
                            "status": "affected",
                            "versionType": "semver"
                        }
                    ]
                },
                {
                    "product": "Linux",
                    "vendor": "Linux",
                    "defaultStatus": "affected",
                    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                    "programFiles": [
                        "include/linux/nsproxy.h",
                        "kernel/fork.c",
                        "kernel/nsproxy.c"
                    ],
                    "versions": [
                        {
                            "version": "7.1",
                            "status": "affected"
                        },
                        {
                            "version": "0",
                            "lessThan": "7.1",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "7.2.11",
                            "lessThanOrEqual": "7.2.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "7.3",
                            "lessThanOrEqual": "*",
                            "status": "unaffected",
                            "versionType": "original_commit_for_fix"
                        }
                    ]
                }
            ],
            "cpeApplicability": [
                {
                    "nodes": [
                        {
                            "operator": "OR",
                            "negate": false,
                            "cpeMatch": [
                                {
                                    "vulnerable": true,
                                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                                    "versionStartIncluding": "7.1",
                                    "versionEndExcluding": "7.2.11"
                                },
                                {
                                    "vulnerable": true,
                                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                                    "versionStartIncluding": "7.1",
                                    "versionEndExcluding": "7.3"
                                },
                                {
                                    "vulnerable": true,
                                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                                    "versionStartIncluding": "5.15.209"
                                },
                                {
                                    "vulnerable": true,
                                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                                    "versionStartIncluding": "6.1.175"
                                },
                                {
                                    "vulnerable": true,
                                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                                    "versionStartIncluding": "6.6.141"
                                },
                                {
                                    "vulnerable": true,
                                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                                    "versionStartIncluding": "6.12.91"
                                },
                                {
                                    "vulnerable": true,
                                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                                    "versionStartIncluding": "6.18.33"
                                },
                                {
                                    "vulnerable": true,
                                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                                    "versionStartIncluding": "7.0.10"
                                }
                            ]
                        }
                    ]
                }
            ],
            "references": [
                {
                    "url": "https://git.kernel.org/stable/c/56fe03a0c05dba4c5f6a23c391f96de1614a098c"
                },
                {
                    "url": "https://git.kernel.org/stable/c/0b6f31a3c0b16066f812e94b52a704174a6f23cd"
                }
            ],
            "title": "unshare: don't drop active namespace references that were never taken",
            "x_generator": {
                "engine": "bippy-1.2.0"
            }
        }
    }
}