{"id":"CVE-2025-21731","revision":"768f5af16873477097e959d310343ff4","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":[]}