{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-45866","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-05-13T15:03:33.080Z","datePublished":"2026-05-27T12:15:46.135Z","dateUpdated":"2026-05-27T12:15:46.135Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-05-27T12:15:46.135Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nserial: caif: fix use-after-free in caif_serial ldisc_close()\n\nThere is a use-after-free bug in caif_serial where handle_tx() may\naccess ser->tty after the tty has been freed.\n\nThe race condition occurs between ldisc_close() and packet transmission:\n\n    CPU 0 (close)                     CPU 1 (xmit)\n    -------------                     ------------\n    ldisc_close()\n      tty_kref_put(ser->tty)\n      [tty may be freed here]\n                     <-- race window -->\n                                      caif_xmit()\n                                        handle_tx()\n                                          tty = ser->tty  // dangling ptr\n                                          tty->ops->write() // UAF!\n      schedule_work()\n        ser_release()\n          unregister_netdevice()\n\nThe root cause is that tty_kref_put() is called in ldisc_close() while\nthe network device is still active and can receive packets.\n\nSince ser and tty have a 1:1 binding relationship with consistent\nlifecycles (ser is allocated in ldisc_open and freed in ser_release\nvia unregister_netdevice, and each ser binds exactly one tty), we can\nsafely defer the tty reference release to ser_release() where the\nnetwork device is unregistered.\n\nFix this by moving tty_kref_put() from ldisc_close() to ser_release(),\nafter unregister_netdevice(). This ensures the tty reference is held\nas long as the network device exists, preventing the UAF.\n\nNote: We save ser->tty before unregister_netdevice() because ser is\nembedded in netdev's private data and will be freed along with netdev\n(needs_free_netdev = true).\n\nHow to reproduce: Add mdelay(500) at the beginning of ldisc_close()\nto widen the race window, then run the reproducer program [1].\n\nNote: There is a separate deadloop issue in handle_tx() when using\nPORT_UNKNOWN serial ports (e.g., /dev/ttyS3 in QEMU without proper\nserial backend). This deadloop exists even without this patch,\nand is likely caused by inconsistency between uart_write_room() and\nuart_write() in serial core. It has been addressed in a separate\npatch [2].\n\nKASAN report:\n\n==================================================================\nBUG: KASAN: slab-use-after-free in handle_tx+0x5d1/0x620\nRead of size 1 at addr ffff8881131e1490 by task caif_uaf_trigge/9929\n\nCall Trace:\n <TASK>\n dump_stack_lvl+0x10e/0x1f0\n print_report+0xd0/0x630\n kasan_report+0xe4/0x120\n handle_tx+0x5d1/0x620\n dev_hard_start_xmit+0x9d/0x6c0\n __dev_queue_xmit+0x6e2/0x4410\n packet_xmit+0x243/0x360\n packet_sendmsg+0x26cf/0x5500\n __sys_sendto+0x4a3/0x520\n __x64_sys_sendto+0xe0/0x1c0\n do_syscall_64+0xc9/0xf80\n entry_SYSCALL_64_after_hwframe+0x77/0x7f\nRIP: 0033:0x7f615df2c0d7\n\nAllocated by task 9930:\n\nFreed by task 64:\n\nLast potentially related work creation:\n\nThe buggy address belongs to the object at ffff8881131e1000\n which belongs to the cache kmalloc-cg-2k of size 2048\nThe buggy address is located 1168 bytes inside of\n freed 2048-byte region [ffff8881131e1000, ffff8881131e1800)\n\nThe buggy address belongs to the physical page:\npage_owner tracks the page as allocated\npage last free pid 9778 tgid 9778 stack trace:\n\nMemory state around the buggy address:\n ffff8881131e1380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb\n ffff8881131e1400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb\n>ffff8881131e1480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb\n                         ^\n ffff8881131e1500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb\n ffff8881131e1580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb\n==================================================================\n[1]: https://gist.github.com/mrpre/f683f244544f7b11e7fa87df9e6c2eeb\n[2]: https://lore.kernel.org/linux-serial/20260204074327.226165-1-jiayuan.chen@linux.dev/T/#u"}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/net/caif/caif_serial.c"],"versions":[{"version":"56e0ef527b184b3de2d7f88c6190812b2b2ac6bf","lessThan":"5e266ba8d330d3b8e5bc198f238cd8901826cfa1","status":"affected","versionType":"git"},{"version":"56e0ef527b184b3de2d7f88c6190812b2b2ac6bf","lessThan":"d3c75db4e0460641dbcd274b40867e252d801da1","status":"affected","versionType":"git"},{"version":"56e0ef527b184b3de2d7f88c6190812b2b2ac6bf","lessThan":"4e63d6f68544ae5269ac9735ae5b69b59b5b8725","status":"affected","versionType":"git"},{"version":"56e0ef527b184b3de2d7f88c6190812b2b2ac6bf","lessThan":"331e2b7051635780edea248dd08ae2026c126f4a","status":"affected","versionType":"git"},{"version":"56e0ef527b184b3de2d7f88c6190812b2b2ac6bf","lessThan":"52731ef4438155cea782fac74e547a327ab9e7c5","status":"affected","versionType":"git"},{"version":"56e0ef527b184b3de2d7f88c6190812b2b2ac6bf","lessThan":"c8c197aaa56b25a2d54f3aa07e27e228d6c08546","status":"affected","versionType":"git"},{"version":"56e0ef527b184b3de2d7f88c6190812b2b2ac6bf","lessThan":"40962f2bf8cdba63af23aec95ad3f49b689e58e2","status":"affected","versionType":"git"},{"version":"56e0ef527b184b3de2d7f88c6190812b2b2ac6bf","lessThan":"308e7e4d0a846359685f40aade023aee7b27284c","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/net/caif/caif_serial.c"],"versions":[{"version":"3.11","status":"affected"},{"version":"0","lessThan":"3.11","status":"unaffected","versionType":"semver"},{"version":"5.10.252","lessThanOrEqual":"5.10.*","status":"unaffected","versionType":"semver"},{"version":"5.15.202","lessThanOrEqual":"5.15.*","status":"unaffected","versionType":"semver"},{"version":"6.1.165","lessThanOrEqual":"6.1.*","status":"unaffected","versionType":"semver"},{"version":"6.6.128","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.75","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.18.14","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"6.19.4","lessThanOrEqual":"6.19.*","status":"unaffected","versionType":"semver"},{"version":"7.0","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.11","versionEndExcluding":"5.10.252"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.11","versionEndExcluding":"5.15.202"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.11","versionEndExcluding":"6.1.165"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.11","versionEndExcluding":"6.6.128"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.11","versionEndExcluding":"6.12.75"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.11","versionEndExcluding":"6.18.14"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.11","versionEndExcluding":"6.19.4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.11","versionEndExcluding":"7.0"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/5e266ba8d330d3b8e5bc198f238cd8901826cfa1"},{"url":"https://git.kernel.org/stable/c/d3c75db4e0460641dbcd274b40867e252d801da1"},{"url":"https://git.kernel.org/stable/c/4e63d6f68544ae5269ac9735ae5b69b59b5b8725"},{"url":"https://git.kernel.org/stable/c/331e2b7051635780edea248dd08ae2026c126f4a"},{"url":"https://git.kernel.org/stable/c/52731ef4438155cea782fac74e547a327ab9e7c5"},{"url":"https://git.kernel.org/stable/c/c8c197aaa56b25a2d54f3aa07e27e228d6c08546"},{"url":"https://git.kernel.org/stable/c/40962f2bf8cdba63af23aec95ad3f49b689e58e2"},{"url":"https://git.kernel.org/stable/c/308e7e4d0a846359685f40aade023aee7b27284c"}],"title":"serial: caif: fix use-after-free in caif_serial ldisc_close()","x_generator":{"engine":"bippy-1.2.0"}}}}