{"id":"CVE-2026-46275","state":"PUBLISHED","title":"Bluetooth: hci_uart: fix UAFs and race conditions in close and init paths","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: hci_uart: fix UAFs and race conditions in close and init paths\n\nVulnerabilities leading to Use-After-Free (UAF) and Null Pointer\nDereference (NPD) conditions were observed in the lifecycle management\nof hci_uart.\n\nThe primary issue arises because the workqueues (init_ready and\nwrite_work) are only flushed/cancelled if the HCI_UART_PROTO_READY\nflag is set during TTY close. If a hangup occurs before setup completes,\nhci_uart_tty_close() skips the teardown of these workqueues and\nproceeds to free the `hu` struct. When the scheduled work executes\nlater, it blindly dereferences the freed `hu` struct.\n\nFurthermore, several data races and UAFs were identified in the teardown\nsequence:\n1. Calling hci_uart_flush() from hci_uart_close() without effectively\n   disabling write_work causes a race condition where both can concurrently\n   double-free hu->tx_skb. This happens because protocol timers can\n   concurrently invoke hci_uart_tx_wakeup() and requeue write_work.\n2. Calling hci_free_dev(hdev) before hu->proto->close(hu) causes a UAF\n   when vendor specific protocol close callbacks dereference hu->hdev.\n3. In the initialization error paths, failing to take the proto_lock\n   write lock before clearing PROTO_READY leads to races with active\n   readers. Additionally, hci_uart_tty_receive() accesses hu->hdev\n   outside the read lock, leading to UAFs if the initialization error\n   path frees hdev concurrently.\n\nFix these synchronization and lifecycle issues by:\n1. Re-ordering hci_uart_tty_close() to clear HCI_UART_PROTO_READY first,\n   followed immediately by a cancel_work_sync(&hu->write_work). Clearing\n   the flag locks out concurrent protocol timers from successfully invoking\n   hci_uart_tx_wakeup(), effectively rendering the cancellation permanent\n   and preventing the tx_skb double-free.\n2. Note: Clearing PROTO_READY early causes hci_uart_close() to skip\n   hu->proto->flush(). This is perfectly safe in the tty_close path\n   because hu->proto->close() executes shortly after, which intrinsically\n   purges all protocol SKB queues and tears down the state.\n3. Relocating hu->proto->close(hu) strictly prior to hci_free_dev(hdev)\n   across all close and error paths to prevent vendor-level UAFs.\n4. Moving the hdev->stat.byte_rx increment in hci_uart_tty_receive()\n   inside the proto_lock read-side critical section to safely synchronize\n   with device unregistration.\n5. Adding cancel_work_sync(&hu->write_work) to hci_uart_close() to safely\n   flush the workqueue before hci_uart_flush() is invoked via the HCI core.\n6. Utilizing cancel_work_sync() instead of disable_work_sync() across\n   all paths to prevent permanently breaking user-space retry capabilities.","publishedAt":"2026-06-08T14:30:54.232Z","updatedAt":"2026-10-19T19:36:56.765Z","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":"3b799254cf6f481460719023d7a18f46651e5e7f","status":"affected","lessThan":"78aad93e938f013d9272fe0ee168f27883afa95c","versionType":"git"},{"version":"3b799254cf6f481460719023d7a18f46651e5e7f","status":"affected","lessThan":"e2d19969c8d9198ecc3090bcd5312ecd503a3339","versionType":"git"},{"version":"3b799254cf6f481460719023d7a18f46651e5e7f","status":"affected","lessThan":"c85cff648a2bc92322912db5f1727ad05afae7b6","versionType":"git"},{"version":"3b799254cf6f481460719023d7a18f46651e5e7f","status":"affected","lessThan":"9d20d48be2c4a071fb015eb09bda2cecd25daf34","versionType":"git"},{"version":"3b799254cf6f481460719023d7a18f46651e5e7f","status":"affected","lessThan":"81c7a3c22a0f2808cf4ae0b4908f59763b23606d","versionType":"git"},{"version":"3b799254cf6f481460719023d7a18f46651e5e7f","status":"affected","lessThan":"192cb0f1ca706d9a1bc36ae0ad5f666d1e4fd894","versionType":"git"},{"version":"3b799254cf6f481460719023d7a18f46651e5e7f","status":"affected","lessThan":"7338031946bd06f6dff149e67b60c4cd083bfea8","versionType":"git"},{"version":"3b799254cf6f481460719023d7a18f46651e5e7f","status":"affected","lessThan":"c1bb9336ae6b54a5f6a353c4bd4ed9a4307e429b","versionType":"git"},{"version":"cd27019bc149f20f12ebec943c2b4c775745a5a0","status":"affected","versionType":"git"},{"version":"aea63181b6fcb6b9ccde1ada9ea51be19c4015af","status":"affected","versionType":"git"},{"version":"0d234d1135dcd8876de0576dac68efd0a87eef87","status":"affected","versionType":"git"},{"version":"3fe978892ab46efc2f3830d9abc015eff72caaf9","status":"affected","versionType":"git"},{"version":"0d987e14bebaf0f67ee7dbefaf6165c62cd1d27f","status":"affected","versionType":"git"},{"version":"4.14.203","status":"affected","lessThan":"4.15","versionType":"semver"},{"version":"4.19.153","status":"affected","lessThan":"4.20","versionType":"semver"},{"version":"5.4.73","status":"affected","lessThan":"5.5","versionType":"semver"},{"version":"5.8.17","status":"affected","lessThan":"5.9","versionType":"semver"},{"version":"5.9.2","status":"affected","lessThan":"5.10","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/bluetooth/hci_ldisc.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.10","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.10","versionType":"semver"},{"version":"5.10.258","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.209","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.175","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.142","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.92","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.34","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.11","status":"unaffected","lessThanOrEqual":"7.0.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/bluetooth/hci_ldisc.c"]}],"references":["https://git.kernel.org/stable/c/78aad93e938f013d9272fe0ee168f27883afa95c","https://git.kernel.org/stable/c/e2d19969c8d9198ecc3090bcd5312ecd503a3339","https://git.kernel.org/stable/c/c85cff648a2bc92322912db5f1727ad05afae7b6","https://git.kernel.org/stable/c/9d20d48be2c4a071fb015eb09bda2cecd25daf34","https://git.kernel.org/stable/c/81c7a3c22a0f2808cf4ae0b4908f59763b23606d","https://git.kernel.org/stable/c/192cb0f1ca706d9a1bc36ae0ad5f666d1e4fd894","https://git.kernel.org/stable/c/7338031946bd06f6dff149e67b60c4cd083bfea8","https://git.kernel.org/stable/c/c1bb9336ae6b54a5f6a353c4bd4ed9a4307e429b","https://cert-portal.siemens.com/productcert/html/ssa-784472.html"],"weaknesses":["CWE-362"],"ingestedAt":"2026-10-29T20:12:07.131Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/46xxx/CVE-2026-46275.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-46275","state":"PUBLISHED","datePublished":"2026-06-08T14:30:54.232Z","dateUpdated":"2026-10-19T19:36:56.765Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-05-13T15:03:33.109Z"},"containers":{"cna":{"title":"Bluetooth: hci_uart: fix UAFs and race conditions in close and init paths","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: hci_uart: fix UAFs and race conditions in close and init paths\n\nVulnerabilities leading to Use-After-Free (UAF) and Null Pointer\nDereference (NPD) conditions were observed in the lifecycle management\nof hci_uart.\n\nThe primary issue arises because the workqueues (init_ready and\nwrite_work) are only flushed/cancelled if the HCI_UART_PROTO_READY\nflag is set during TTY close. If a hangup occurs before setup completes,\nhci_uart_tty_close() skips the teardown of these workqueues and\nproceeds to free the `hu` struct. When the scheduled work executes\nlater, it blindly dereferences the freed `hu` struct.\n\nFurthermore, several data races and UAFs were identified in the teardown\nsequence:\n1. Calling hci_uart_flush() from hci_uart_close() without effectively\n   disabling write_work causes a race condition where both can concurrently\n   double-free hu->tx_skb. This happens because protocol timers can\n   concurrently invoke hci_uart_tx_wakeup() and requeue write_work.\n2. Calling hci_free_dev(hdev) before hu->proto->close(hu) causes a UAF\n   when vendor specific protocol close callbacks dereference hu->hdev.\n3. In the initialization error paths, failing to take the proto_lock\n   write lock before clearing PROTO_READY leads to races with active\n   readers. Additionally, hci_uart_tty_receive() accesses hu->hdev\n   outside the read lock, leading to UAFs if the initialization error\n   path frees hdev concurrently.\n\nFix these synchronization and lifecycle issues by:\n1. Re-ordering hci_uart_tty_close() to clear HCI_UART_PROTO_READY first,\n   followed immediately by a cancel_work_sync(&hu->write_work). Clearing\n   the flag locks out concurrent protocol timers from successfully invoking\n   hci_uart_tx_wakeup(), effectively rendering the cancellation permanent\n   and preventing the tx_skb double-free.\n2. Note: Clearing PROTO_READY early causes hci_uart_close() to skip\n   hu->proto->flush(). This is perfectly safe in the tty_close path\n   because hu->proto->close() executes shortly after, which intrinsically\n   purges all protocol SKB queues and tears down the state.\n3. Relocating hu->proto->close(hu) strictly prior to hci_free_dev(hdev)\n   across all close and error paths to prevent vendor-level UAFs.\n4. Moving the hdev->stat.byte_rx increment in hci_uart_tty_receive()\n   inside the proto_lock read-side critical section to safely synchronize\n   with device unregistration.\n5. Adding cancel_work_sync(&hu->write_work) to hci_uart_close() to safely\n   flush the workqueue before hci_uart_flush() is invoked via the HCI core.\n6. Utilizing cancel_work_sync() instead of disable_work_sync() across\n   all paths to prevent permanently breaking user-space retry capabilities."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"3b799254cf6f481460719023d7a18f46651e5e7f","status":"affected","lessThan":"78aad93e938f013d9272fe0ee168f27883afa95c","versionType":"git"},{"version":"3b799254cf6f481460719023d7a18f46651e5e7f","status":"affected","lessThan":"e2d19969c8d9198ecc3090bcd5312ecd503a3339","versionType":"git"},{"version":"3b799254cf6f481460719023d7a18f46651e5e7f","status":"affected","lessThan":"c85cff648a2bc92322912db5f1727ad05afae7b6","versionType":"git"},{"version":"3b799254cf6f481460719023d7a18f46651e5e7f","status":"affected","lessThan":"9d20d48be2c4a071fb015eb09bda2cecd25daf34","versionType":"git"},{"version":"3b799254cf6f481460719023d7a18f46651e5e7f","status":"affected","lessThan":"81c7a3c22a0f2808cf4ae0b4908f59763b23606d","versionType":"git"},{"version":"3b799254cf6f481460719023d7a18f46651e5e7f","status":"affected","lessThan":"192cb0f1ca706d9a1bc36ae0ad5f666d1e4fd894","versionType":"git"},{"version":"3b799254cf6f481460719023d7a18f46651e5e7f","status":"affected","lessThan":"7338031946bd06f6dff149e67b60c4cd083bfea8","versionType":"git"},{"version":"3b799254cf6f481460719023d7a18f46651e5e7f","status":"affected","lessThan":"c1bb9336ae6b54a5f6a353c4bd4ed9a4307e429b","versionType":"git"},{"version":"cd27019bc149f20f12ebec943c2b4c775745a5a0","status":"affected","versionType":"git"},{"version":"aea63181b6fcb6b9ccde1ada9ea51be19c4015af","status":"affected","versionType":"git"},{"version":"0d234d1135dcd8876de0576dac68efd0a87eef87","status":"affected","versionType":"git"},{"version":"3fe978892ab46efc2f3830d9abc015eff72caaf9","status":"affected","versionType":"git"},{"version":"0d987e14bebaf0f67ee7dbefaf6165c62cd1d27f","status":"affected","versionType":"git"},{"version":"4.14.203","status":"affected","lessThan":"4.15","versionType":"semver"},{"version":"4.19.153","status":"affected","lessThan":"4.20","versionType":"semver"},{"version":"5.4.73","status":"affected","lessThan":"5.5","versionType":"semver"},{"version":"5.8.17","status":"affected","lessThan":"5.9","versionType":"semver"},{"version":"5.9.2","status":"affected","lessThan":"5.10","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/bluetooth/hci_ldisc.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.10","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.10","versionType":"semver"},{"version":"5.10.258","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.209","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.175","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.142","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.92","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.34","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.11","status":"unaffected","lessThanOrEqual":"7.0.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/bluetooth/hci_ldisc.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/78aad93e938f013d9272fe0ee168f27883afa95c"},{"url":"https://git.kernel.org/stable/c/e2d19969c8d9198ecc3090bcd5312ecd503a3339"},{"url":"https://git.kernel.org/stable/c/c85cff648a2bc92322912db5f1727ad05afae7b6"},{"url":"https://git.kernel.org/stable/c/9d20d48be2c4a071fb015eb09bda2cecd25daf34"},{"url":"https://git.kernel.org/stable/c/81c7a3c22a0f2808cf4ae0b4908f59763b23606d"},{"url":"https://git.kernel.org/stable/c/192cb0f1ca706d9a1bc36ae0ad5f666d1e4fd894"},{"url":"https://git.kernel.org/stable/c/7338031946bd06f6dff149e67b60c4cd083bfea8"},{"url":"https://git.kernel.org/stable/c/c1bb9336ae6b54a5f6a353c4bd4ed9a4307e429b"}],"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 - Exploitation requires local TTY control (TIOCSETD to N_HCI, HCIUARTSETPROTO ioctl, hangup/close) gated by CAP_NET_ADMIN at hci_uart_tty_open(); the bugs are in driver lifecycle teardown, not in processing of remote Bluetooth over-the-air packets.\nAC:L - The attacker controls both sides of every race by concurrently opening/closing the TTY line discipline, issuing HCIUART ioctls, and timing hangup against in-flight workqueues and protocol timers; UAF conditions are reliably winnable without luck-dependent memory layout.\nPR:L - hci_uart_tty_open() explicitly requires CAP_NET_ADMIN, and adapter teardown paths are similarly admin-gated; CAP_NET_ADMIN is obtainable by an unprivileged user inside a user namespace, satisfying the Low privileges threshold rather than High.\nUI:N - Once the attacker has the required local TTY/HCI access, triggering the UAF or double-free races requires no action from a separate victim user.\nS:U - The vulnerability corrupts kernel heap memory within the kernel's own security boundary; successful exploitation yields kernel privilege escalation, not a cross-boundary escape such as VM or sandbox breakout.\nC:H - Multiple use-after-free conditions on the hci_uart and hci_dev structures allow dereferencing attacker-influenced freed memory, providing a standard kernel info-leak primitive consistent with UAF severity guidance.\nI:H - The UAF and hu->tx_skb double-free races enable control of freed slab objects and heap grooming, providing a path to arbitrary kernel memory corruption and potential code execution in kernel context.\nA:H - Use-after-free and double-free in kernel workqueue and teardown paths reliably cause kernel oops or panic, and can be triggered repeatedly to deny availability of the affected system."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T12:30:58.918Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.10","versionEndExcluding":"5.10.258"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.10","versionEndExcluding":"5.15.209"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.10","versionEndExcluding":"6.1.175"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.10","versionEndExcluding":"6.6.142"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.10","versionEndExcluding":"6.12.92"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.10","versionEndExcluding":"6.18.34"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.10","versionEndExcluding":"7.0.11"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.10","versionEndExcluding":"7.1"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.14.203"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.19.153"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.4.73"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.8.17"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.9.2"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"affected":[{"vendor":"Siemens","product":"SIMATIC S7-1500 TM MFP - GNU/Linux subsystem","defaultStatus":"unknown","versions":[{"version":"0","status":"affected","lessThan":"*","versionType":"custom"}]}],"references":[{"url":"https://cert-portal.siemens.com/productcert/html/ssa-784472.html"}],"providerMetadata":{"shortName":"siemens-SADP","orgId":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e","dateUpdated":"2026-10-15T01:21:24.779Z"},"x_adpType":"supplier"},{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-46275","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"version":"2.0.3","timestamp":"2026-10-16T15:21:36.754865Z"}}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-362","lang":"en","type":"CWE","description":"CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')"}]}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-19T19:36:56.765Z"}}]}}}