{"id":"CVE-2021-47459","state":"PUBLISHED","title":"can: j1939: j1939_netdev_start(): fix UAF for rx_kref of j1939_priv","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ncan: j1939: j1939_netdev_start(): fix UAF for rx_kref of j1939_priv\n\nIt will trigger UAF for rx_kref of j1939_priv as following.\n\n        cpu0                                    cpu1\nj1939_sk_bind(socket0, ndev0, ...)\nj1939_netdev_start\n                                        j1939_sk_bind(socket1, ndev0, ...)\n                                        j1939_netdev_start\nj1939_priv_set\n                                        j1939_priv_get_by_ndev_locked\nj1939_jsk_add\n.....\nj1939_netdev_stop\nkref_put_lock(&priv->rx_kref, ...)\n                                        kref_get(&priv->rx_kref, ...)\n                                        REFCOUNT_WARN(\"addition on 0;...\")\n\n====================================================\nrefcount_t: addition on 0; use-after-free.\nWARNING: CPU: 1 PID: 20874 at lib/refcount.c:25 refcount_warn_saturate+0x169/0x1e0\nRIP: 0010:refcount_warn_saturate+0x169/0x1e0\nCall Trace:\n j1939_netdev_start+0x68b/0x920\n j1939_sk_bind+0x426/0xeb0\n ? security_socket_bind+0x83/0xb0\n\nThe rx_kref's kref_get() and kref_put() should use j1939_netdev_lock to\nprotect.","publishedAt":"2024-05-22T06:23:21.061Z","updatedAt":"2026-08-05T08:47:56.231Z","severity":{"score":7.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"9d71dd0c70099914fcd063135da3c580865e924c","status":"affected","lessThan":"a0e47d2833b4f65e6c799f28c6b636d36b8b936d","versionType":"git"},{"version":"9d71dd0c70099914fcd063135da3c580865e924c","status":"affected","lessThan":"864e77771a24c877aaf53aee019f78619cbcd668","versionType":"git"},{"version":"9d71dd0c70099914fcd063135da3c580865e924c","status":"affected","lessThan":"6e8811707e2df0c6ba920f0cad3a3bca7b42132f","versionType":"git"},{"version":"9d71dd0c70099914fcd063135da3c580865e924c","status":"affected","lessThan":"d9d52a3ebd284882f5562c88e55991add5d01586","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/can/j1939/main.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.4","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.4","versionType":"semver"},{"version":"5.4.156","status":"unaffected","lessThanOrEqual":"5.4.*","versionType":"semver"},{"version":"5.10.76","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.14.15","status":"unaffected","lessThanOrEqual":"5.14.*","versionType":"semver"},{"version":"5.15","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/can/j1939/main.c"]}],"references":["https://git.kernel.org/stable/c/a0e47d2833b4f65e6c799f28c6b636d36b8b936d","https://git.kernel.org/stable/c/864e77771a24c877aaf53aee019f78619cbcd668","https://git.kernel.org/stable/c/6e8811707e2df0c6ba920f0cad3a3bca7b42132f","https://git.kernel.org/stable/c/d9d52a3ebd284882f5562c88e55991add5d01586"],"weaknesses":[],"ingestedAt":"2026-10-29T19:49:19.404Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2021/47xxx/CVE-2021-47459.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2021-47459","state":"PUBLISHED","datePublished":"2024-05-22T06:23:21.061Z","dateUpdated":"2026-08-05T08:47:56.231Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2024-05-22T06:20:56.197Z"},"containers":{"cna":{"title":"can: j1939: j1939_netdev_start(): fix UAF for rx_kref of j1939_priv","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\ncan: j1939: j1939_netdev_start(): fix UAF for rx_kref of j1939_priv\n\nIt will trigger UAF for rx_kref of j1939_priv as following.\n\n        cpu0                                    cpu1\nj1939_sk_bind(socket0, ndev0, ...)\nj1939_netdev_start\n                                        j1939_sk_bind(socket1, ndev0, ...)\n                                        j1939_netdev_start\nj1939_priv_set\n                                        j1939_priv_get_by_ndev_locked\nj1939_jsk_add\n.....\nj1939_netdev_stop\nkref_put_lock(&priv->rx_kref, ...)\n                                        kref_get(&priv->rx_kref, ...)\n                                        REFCOUNT_WARN(\"addition on 0;...\")\n\n====================================================\nrefcount_t: addition on 0; use-after-free.\nWARNING: CPU: 1 PID: 20874 at lib/refcount.c:25 refcount_warn_saturate+0x169/0x1e0\nRIP: 0010:refcount_warn_saturate+0x169/0x1e0\nCall Trace:\n j1939_netdev_start+0x68b/0x920\n j1939_sk_bind+0x426/0xeb0\n ? security_socket_bind+0x83/0xb0\n\nThe rx_kref's kref_get() and kref_put() should use j1939_netdev_lock to\nprotect."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"9d71dd0c70099914fcd063135da3c580865e924c","status":"affected","lessThan":"a0e47d2833b4f65e6c799f28c6b636d36b8b936d","versionType":"git"},{"version":"9d71dd0c70099914fcd063135da3c580865e924c","status":"affected","lessThan":"864e77771a24c877aaf53aee019f78619cbcd668","versionType":"git"},{"version":"9d71dd0c70099914fcd063135da3c580865e924c","status":"affected","lessThan":"6e8811707e2df0c6ba920f0cad3a3bca7b42132f","versionType":"git"},{"version":"9d71dd0c70099914fcd063135da3c580865e924c","status":"affected","lessThan":"d9d52a3ebd284882f5562c88e55991add5d01586","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/can/j1939/main.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.4","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.4","versionType":"semver"},{"version":"5.4.156","status":"unaffected","lessThanOrEqual":"5.4.*","versionType":"semver"},{"version":"5.10.76","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.14.15","status":"unaffected","lessThanOrEqual":"5.14.*","versionType":"semver"},{"version":"5.15","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/can/j1939/main.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/a0e47d2833b4f65e6c799f28c6b636d36b8b936d"},{"url":"https://git.kernel.org/stable/c/864e77771a24c877aaf53aee019f78619cbcd668"},{"url":"https://git.kernel.org/stable/c/6e8811707e2df0c6ba920f0cad3a3bca7b42132f"},{"url":"https://git.kernel.org/stable/c/d9d52a3ebd284882f5562c88e55991add5d01586"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - The bug is reached only through local syscalls (socket/bind/close) into j1939_sk_bind → j1939_netdev_start/stop; it is not triggered by receiving CAN/J1939 frames from the wire.\nAC:L - The race is fully attacker-controlled by opening multiple J1939 sockets and concurrently binding/closing them on the same CAN interface, as demonstrated by the syzbot threaded reproducers.\nPR:L - Creating and binding CAN_J1939 sockets requires no capabilities; an unprivileged user can reach the path on an existing UP CAN device or by creating vcan in a user/net namespace with namespaced CAP_NET_ADMIN.\nUI:N - Exploitation requires no victim action beyond the attacker’s own socket operations.\nS:U - This is a standard in-kernel memory-safety flaw affecting the host kernel authority, with no VM/IOMMU/sandbox boundary crossing.\nC:H - The vulnerability is a use-after-free on j1939_priv refcounting; UAF enables reclaim/spray of the freed object and arbitrary kernel memory disclosure.\nI:H - Use-after-free of j1939_priv state enables heap manipulation and write primitives sufficient for control-flow hijacking or arbitrary kernel writes.\nA:H - The UAF reliably produces refcount warnings and kernel oops/crash conditions even without full exploitation, denying availability."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T08:47:56.231Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.4","versionEndExcluding":"5.4.156"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.4","versionEndExcluding":"5.10.76"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.4","versionEndExcluding":"5.14.15"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.4","versionEndExcluding":"5.15"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CVE Program Container","references":[{"url":"https://git.kernel.org/stable/c/a0e47d2833b4f65e6c799f28c6b636d36b8b936d","tags":["x_transferred"]},{"url":"https://git.kernel.org/stable/c/864e77771a24c877aaf53aee019f78619cbcd668","tags":["x_transferred"]},{"url":"https://git.kernel.org/stable/c/6e8811707e2df0c6ba920f0cad3a3bca7b42132f","tags":["x_transferred"]},{"url":"https://git.kernel.org/stable/c/d9d52a3ebd284882f5562c88e55991add5d01586","tags":["x_transferred"]}],"providerMetadata":{"shortName":"CVE","orgId":"af854a3a-2127-422b-91ae-364da2661108","dateUpdated":"2024-08-04T05:39:59.451Z"}},{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2021-47459","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"version":"2.0.3","timestamp":"2024-09-10T15:36:14.848678Z"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2024-09-11T17:33:25.941Z"}}]}}}