{"id":"CVE-2026-98983","revision":null,"records":[{"revision":"843d642fc8954ea1b6ee98e7d6a4cc91","observedAt":"2026-10-23T16:01:20.601+00:00","statement":{"source":"cve-program","id":"CVE-2026-98983","aliases":[],"title":"unshare: don't drop active namespace references that were never taken","description":"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.","state":0,"publishedAt":"2026-10-23T12:20:00.918+00:00","modifiedAt":"2026-10-23T12:20:00.918+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"unaffected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"include/linux/nsproxy.h\",\n \"kernel/fork.c\",\n \"kernel/nsproxy.c\"\n ],\n \"versions\": [\n {\n \"version\": \"a98621a0f187a934c115dcfe79a49520ae892111\",\n \"lessThan\": \"56fe03a0c05dba4c5f6a23c391f96de1614a098c\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"a98621a0f187a934c115dcfe79a49520ae892111\",\n \"lessThan\": \"0b6f31a3c0b16066f812e94b52a704174a6f23cd\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"27ae6b17c9ba7ff353ab0906297f08aa845782b4\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"297261b343371c4f0b31055d53d285138ec21565\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"813a47b0309097da71781ee4ac11922e39b67d55\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"6e608e3e5ce12ce7fd21e46212eccca37f917d0e\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"a261fccdb4ac58ec5ba6aa1d92a6cc418fff301f\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"665dc1ed16357988d439fc5bbc860ee36f540d81\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"5.15.209\",\n \"lessThan\": \"5.16\",\n \"status\": \"affected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.1.175\",\n \"lessThan\": \"6.2\",\n \"status\": \"affected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.6.141\",\n \"lessThan\": \"6.7\",\n \"status\": \"affected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.12.91\",\n \"lessThan\": \"6.13\",\n \"status\": \"affected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.18.33\",\n \"lessThan\": \"6.19\",\n \"status\": \"affected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"7.0.10\",\n \"lessThan\": \"7.1\",\n \"status\": \"affected\",\n \"versionType\": \"semver\"\n }\n ]\n }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"affected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"include/linux/nsproxy.h\",\n \"kernel/fork.c\",\n \"kernel/nsproxy.c\"\n ],\n \"versions\": [\n {\n \"version\": \"7.1\",\n \"status\": \"affected\"\n },\n {\n \"version\": \"0\",\n \"lessThan\": \"7.1\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"7.2.11\",\n \"lessThanOrEqual\": \"7.2.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"7.3\",\n \"lessThanOrEqual\": \"*\",\n \"status\": \"unaffected\",\n \"versionType\": \"original_commit_for_fix\"\n }\n ]\n }"}],"metrics":[],"references":["https://git.kernel.org/stable/c/56fe03a0c05dba4c5f6a23c391f96de1614a098c","https://git.kernel.org/stable/c/0b6f31a3c0b16066f812e94b52a704174a6f23cd"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-98983","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-98983","identifiers":["CVE-2026-98983"]},"retained":false,"historicalAffected":[]}],"coverage":[{"source":"cisa-kev:global","scope":"Complete CISA KEV catalog; all vendors. Missing entries do not establish absence of exploitation.","generation":"2026-10-28T06:06:22.8608156+00:00","complete":true,"records":1760,"lastAttemptAt":"2026-10-28T06:06:22.8608156+00:00","lastSuccessAt":"2026-10-28T06:06:22.9998161+00:00","error":null,"lastVerifiedAt":"2026-10-28T06:06:22.9998165+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"cve-program","scope":"Official CVE Program baseline and cumulative hourly delta; all vendors, published and rejected records","generation":"cve-d2186f400c54d65f61687f78bb1a00d184d2e215877d0194d7ed70caee809a44-445379b0c53fd1f8d253c8a14ff9901d849a8a0a854aa4f1d7de3dcccb1e5f13","complete":true,"records":415520,"lastAttemptAt":"2026-10-28T06:06:22.1141459+00:00","lastSuccessAt":"2026-10-28T06:06:22.0953342+00:00","error":null,"lastVerifiedAt":"2026-10-28T06:06:22.1141459+00:00","snapshotPublishedAt":"2026-10-28T05:18:29+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"euvd","scope":"Rolling EUVD lookups of CVE aliases in current public OSV archives; 500 identifiers per refresh, rechecked after 48 hours. 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Not a global EPSS backfill.","generation":"2026-10-28T06:06:22.8608156+00:00","complete":true,"records":1093,"lastAttemptAt":"2026-10-28T06:06:22.8608156+00:00","lastSuccessAt":"2026-10-28T06:06:23.0013193+00:00","error":null,"lastVerifiedAt":"2026-10-28T06:06:23.0013198+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"nvd","scope":"Rolling NVD lookups of CVE aliases in current public OSV archives; 500 identifiers per refresh, rechecked after 48 hours. Not a global NVD catalog. Successful not-found lookups count as checked; they do not imply withdrawal or safety. No reader inventory is sent.","generation":"enrichment-8d16a738328646698f9217d8ea11893c","complete":true,"records":13449,"lastAttemptAt":"2026-10-28T06:06:25.7470666+00:00","lastSuccessAt":"2026-10-27T22:48:29.491+00:00","error":null,"lastVerifiedAt":"2026-10-27T22:48:29.491+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":13514,"expectedIdentifiers":13514,"failedIdentifiers":0},{"source":"osv:Go","scope":"Complete OSV Go ecosystem archive, including withdrawn and malicious-package source records; statement counts are not unique CVE counts","generation":"go-f7cb12508d9e6a348c8a60f772ed85529cc80cd2ff853da1099b57754b20e943","complete":true,"records":9790,"lastAttemptAt":"2026-10-28T06:06:22.7444146+00:00","lastSuccessAt":"2026-10-27T21:49:03.9756799+00:00","error":null,"lastVerifiedAt":"2026-10-28T06:06:22.7444146+00:00","snapshotPublishedAt":"2026-10-27T21:48:11+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"osv:NuGet","scope":"Complete OSV NuGet ecosystem archive, including GitHub Advisory Database records; NuGet version matching only","generation":"nuget-72e5e79de0026dd0562d40734074a2236a06886643d67182b8381eaee757dbf7","complete":true,"records":1966,"lastAttemptAt":"2026-10-28T06:06:22.1709566+00:00","lastSuccessAt":"2026-10-27T21:46:38.0277323+00:00","error":null,"lastVerifiedAt":"2026-10-28T06:06:22.1709566+00:00","snapshotPublishedAt":"2026-10-27T21:18:15+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"osv:crates.io","scope":"Complete OSV crates.io ecosystem archive, including withdrawn and malicious-package source records; statement counts are not unique CVE counts","generation":"crates.io-3a5b306d60fc44677a03a8afc99d87e6c5402770ef68d560f94a8c3ad3802b75","complete":true,"records":3001,"lastAttemptAt":"2026-10-28T06:06:22.7572796+00:00","lastSuccessAt":"2026-10-27T16:45:49.0050993+00:00","error":null,"lastVerifiedAt":"2026-10-28T06:06:22.7572796+00:00","snapshotPublishedAt":"2026-10-27T16:33:43+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"osv:npm","scope":"Complete OSV npm ecosystem archive, including withdrawn and malicious-package source records; statement counts are not unique CVE counts","generation":"npm-5f3141cf1b985319fe2c9d9b1b1aab03f442c3a2272590c3c2e44d5d3d31bfb3","complete":true,"records":230854,"lastAttemptAt":"2026-10-28T06:06:22.6466834+00:00","lastSuccessAt":"2026-10-28T02:53:16.9493663+00:00","error":null,"lastVerifiedAt":"2026-10-28T06:06:22.6466834+00:00","snapshotPublishedAt":"2026-10-28T02:33:06+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null}]}