{"id":"CVE-2025-21731","revision":null,"records":[{"revision":"768f5af16873477097e959d310343ff4","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2025-21731","aliases":[],"title":"nbd: don't allow reconnect after disconnect","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnbd: don't allow reconnect after disconnect\n\nFollowing process can cause nbd_config UAF:\n\n1) grab nbd_config temporarily;\n\n2) nbd_genl_disconnect() flush all recv_work() and release the\ninitial reference:\n\n nbd_genl_disconnect\n nbd_disconnect_and_put\n nbd_disconnect\n flush_workqueue(nbd->recv_workq)\n if (test_and_clear_bit(NBD_RT_HAS_CONFIG_REF, ...))\n nbd_config_put\n -> due to step 1), reference is still not zero\n\n3) nbd_genl_reconfigure() queue recv_work() again;\n\n nbd_genl_reconfigure\n config = nbd_get_config_unlocked(nbd)\n if (!config)\n -> succeed\n if (!test_bit(NBD_RT_BOUND, ...))\n -> succeed\n nbd_reconnect_socket\n queue_work(nbd->recv_workq, &args->work)\n\n4) step 1) release the reference;\n\n5) Finially, recv_work() will trigger UAF:\n\n recv_work\n nbd_config_put(nbd)\n -> nbd_config is freed\n atomic_dec(&config->recv_threads)\n -> UAF\n\nFix the problem by clearing NBD_RT_BOUND in nbd_genl_disconnect(), so\nthat nbd_genl_reconfigure() will fail.","state":0,"publishedAt":"2025-02-27T02:07:35.927+00:00","modifiedAt":"2026-10-15T01:03:51.467+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 \"drivers/block/nbd.c\"\n ],\n \"versions\": [\n {\n \"version\": \"b7aa3d39385dc2d95899f9e379623fef446a2acd\",\n \"lessThan\": \"e70a578487a47d7cf058904141e586684d1c3381\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"b7aa3d39385dc2d95899f9e379623fef446a2acd\",\n \"lessThan\": \"6bef6222a3f6c7adb6396f77f25a3579d821b09a\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"b7aa3d39385dc2d95899f9e379623fef446a2acd\",\n \"lessThan\": \"e3be8862d73cac833e0fb7602636c19c6cb94b11\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"b7aa3d39385dc2d95899f9e379623fef446a2acd\",\n \"lessThan\": \"e7343fa33751cb07c1c56b666bf37cfca357130e\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"b7aa3d39385dc2d95899f9e379623fef446a2acd\",\n \"lessThan\": \"d208d2c52b652913b5eefc8ca434b0d6b757f68f\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"b7aa3d39385dc2d95899f9e379623fef446a2acd\",\n \"lessThan\": \"a8ee6ecde2b7bfb58c8a3afe8a9d2b848f580739\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"b7aa3d39385dc2d95899f9e379623fef446a2acd\",\n \"lessThan\": \"9793bd5ae4bdbdb2dde401a3cab94a6bfd05e302\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"b7aa3d39385dc2d95899f9e379623fef446a2acd\",\n \"lessThan\": \"844b8cdc681612ff24df62cdefddeab5772fadf1\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\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 \"drivers/block/nbd.c\"\n ],\n \"versions\": [\n {\n \"version\": \"4.12\",\n \"status\": \"affected\"\n },\n {\n \"version\": \"0\",\n \"lessThan\": \"4.12\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"5.4.291\",\n \"lessThanOrEqual\": \"5.4.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"5.10.235\",\n \"lessThanOrEqual\": \"5.10.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"5.15.179\",\n \"lessThanOrEqual\": \"5.15.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.1.129\",\n \"lessThanOrEqual\": \"6.1.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.6.76\",\n \"lessThanOrEqual\": \"6.6.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.12.13\",\n \"lessThanOrEqual\": \"6.12.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.13.2\",\n \"lessThanOrEqual\": \"6.13.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.14\",\n \"lessThanOrEqual\": \"*\",\n \"status\": \"unaffected\",\n \"versionType\": \"original_commit_for_fix\"\n }\n ]\n }"}],"metrics":[],"references":["https://git.kernel.org/stable/c/e70a578487a47d7cf058904141e586684d1c3381","https://git.kernel.org/stable/c/6bef6222a3f6c7adb6396f77f25a3579d821b09a","https://git.kernel.org/stable/c/e3be8862d73cac833e0fb7602636c19c6cb94b11","https://git.kernel.org/stable/c/e7343fa33751cb07c1c56b666bf37cfca357130e","https://git.kernel.org/stable/c/d208d2c52b652913b5eefc8ca434b0d6b757f68f","https://git.kernel.org/stable/c/a8ee6ecde2b7bfb58c8a3afe8a9d2b848f580739","https://git.kernel.org/stable/c/9793bd5ae4bdbdb2dde401a3cab94a6bfd05e302","https://git.kernel.org/stable/c/844b8cdc681612ff24df62cdefddeab5772fadf1"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2025-21731","license":"CVE Program Terms of Use","key":"cve-program:CVE-2025-21731","identifiers":["CVE-2025-21731"]},"retained":false,"historicalAffected":[]}],"coverage":[{"source":"cisa-kev:global","scope":"Complete CISA KEV catalog; all vendors. Missing entries do not establish absence of exploitation.","generation":"2026-11-09T19:02:11.0282238+00:00","complete":true,"records":1772,"lastAttemptAt":"2026-11-09T19:02:11.0282238+00:00","lastSuccessAt":"2026-11-09T19:02:11.2511726+00:00","error":null,"lastVerifiedAt":"2026-11-09T19:02:11.2511728+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-24e6fde7b744113daefb8f6135035fb8a5c69c9617c9c0d40574a0376532ffd3-da82b7f3c08c0a1c809bacbfac0a567c645c18f0205247304bfc7e4ee4c02653","complete":true,"records":421491,"lastAttemptAt":"2026-11-09T19:02:10.4293016+00:00","lastSuccessAt":"2026-11-09T18:02:17.6122603+00:00","error":null,"lastVerifiedAt":"2026-11-09T19:02:10.4293016+00:00","snapshotPublishedAt":"2026-11-09T17:19:01+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. Not a global EUVD catalog. Successful not-found lookups count as checked; they do not imply withdrawal or safety. No reader inventory is sent.","generation":"enrichment-f1df18dfb77f437e9e2ee1dd548e1f15","complete":false,"records":13655,"lastAttemptAt":"2026-11-09T19:14:35.1855237+00:00","lastSuccessAt":"2026-11-09T19:14:35.178+00:00","error":null,"lastVerifiedAt":"2026-11-09T19:14:35.178+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":13398,"expectedIdentifiers":13707,"failedIdentifiers":0},{"source":"first-epss:nuget","scope":"FIRST EPSS for explicit CVE aliases in the collected public NuGet archive. Not a global EPSS backfill.","generation":"2026-11-09T19:02:11.0282238+00:00","complete":true,"records":1096,"lastAttemptAt":"2026-11-09T19:02:11.0282238+00:00","lastSuccessAt":"2026-11-09T19:02:11.2551731+00:00","error":null,"lastVerifiedAt":"2026-11-09T19:02:11.2551735+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-9c7aae9a77ad4fe48f16e3014ae326fa","complete":true,"records":13667,"lastAttemptAt":"2026-11-09T19:02:43.2420437+00:00","lastSuccessAt":"2026-11-09T19:02:43.234+00:00","error":null,"lastVerifiedAt":"2026-11-09T19:02:43.234+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":13707,"expectedIdentifiers":13707,"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-980593e6977a6d1b4fb1eed5a1ffe88a468736f89f0a06f710924ad59132c023","complete":true,"records":9914,"lastAttemptAt":"2026-11-09T19:02:10.7853332+00:00","lastSuccessAt":"2026-11-08T11:07:07.068788+00:00","error":null,"lastVerifiedAt":"2026-11-09T19:02:10.7853332+00:00","snapshotPublishedAt":"2026-11-08T11:02:46+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-712163772d637a9cfaa34d4241efb9e9d0ccd6149596c672c613d362f44af841","complete":true,"records":1971,"lastAttemptAt":"2026-11-09T19:02:10.5860178+00:00","lastSuccessAt":"2026-11-09T18:02:23.0088273+00:00","error":null,"lastVerifiedAt":"2026-11-09T19:02:10.5860178+00:00","snapshotPublishedAt":"2026-11-09T17:03:01+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-761ecc9061239b0da572dc9254c6f384c1d19339eb08408c436647a2f26129e9","complete":true,"records":3064,"lastAttemptAt":"2026-11-09T19:02:10.8954054+00:00","lastSuccessAt":"2026-11-09T17:05:03.4044794+00:00","error":null,"lastVerifiedAt":"2026-11-09T19:02:10.8954054+00:00","snapshotPublishedAt":"2026-11-09T16:33:20+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-e3fec63b2a5926ae79916bc9569f5c1069b095db78f2be319f909e69e8e6d7d3","complete":true,"records":231313,"lastAttemptAt":"2026-11-09T19:02:10.6843987+00:00","lastSuccessAt":"2026-11-09T18:04:48.1910635+00:00","error":null,"lastVerifiedAt":"2026-11-09T19:02:10.6843987+00:00","snapshotPublishedAt":"2026-11-09T17:33:10+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null}]}