{"id":"CVE-2026-53194","summary":"USB: serial: kl5kusb105: fix bulk-out buffer overflow","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nUSB: serial: kl5kusb105: fix bulk-out buffer overflow\n\nklsi_105_prepare_write_buffer() is called by the generic write path\nwith the bulk-out buffer and its size (bulk_out_size, 64 bytes). It\nstores a two-byte length header at the start of the buffer and copies\nthe payload from the write fifo starting at buf + KLSI_HDR_LEN, but\npasses the full buffer size as the number of bytes to copy:\n\n  count = kfifo_out_locked(&port-\u003ewrite_fifo, buf + KLSI_HDR_LEN,\n                           size, &port-\u003elock);\n\nWhen the fifo holds at least size bytes, size bytes are copied starting\ntwo bytes into the size-byte buffer, writing KLSI_HDR_LEN bytes past its\nend. Copy at most size - KLSI_HDR_LEN bytes instead, leaving room for\nthe header as safe_serial already does.\n\nWriting bulk_out_size or more bytes to the tty triggers a slab\nout-of-bounds write, observed with KASAN by emulating the device with\ndummy_hcd and raw-gadget:\n\n  BUG: KASAN: slab-out-of-bounds in kfifo_copy_out+0x83/0xc0\n  Write of size 64 at addr ffff888112c62202 by task python3\n   kfifo_copy_out\n   klsi_105_prepare_write_buffer [kl5kusb105]\n   usb_serial_generic_write_start [usbserial]\n  Allocated by task 139:\n   usb_serial_probe [usbserial]\n  The buggy address is located 2 bytes inside of allocated 64-byte region\n\nThe out-of-bounds write no longer occurs with this change applied.","modified":"2026-07-08T08:09:46.622657905Z","published":"2026-06-25T08:39:05.017Z","related":["CGA-v8vp-2hfp-7r6c"],"database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/53xxx/CVE-2026-53194.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/0a57320f71941d4e0b1307453c9a1f0939afe666"},{"type":"WEB","url":"https://git.kernel.org/stable/c/14147b7963685957839c76ba8094924e22777d79"},{"type":"WEB","url":"https://git.kernel.org/stable/c/372f33ebed747d91870f57c0a2e62884a870bffa"},{"type":"WEB","url":"https://git.kernel.org/stable/c/60af1fd82983c26604102e63a3fcc822c186cceb"},{"type":"WEB","url":"https://git.kernel.org/stable/c/70d86e355c564b5510fde61361df014f5476c83e"},{"type":"WEB","url":"https://git.kernel.org/stable/c/96d47e40bf9db4a9efd5c8fb53287a508d165f14"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a1288cd700f721c1a119c4f1e8efa234e59caada"},{"type":"WEB","url":"https://git.kernel.org/stable/c/bde742b076cbe26ecc89c8c68c76ae076a524d02"},{"type":"WEB","url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-53194.json"},{"type":"ADVISORY","url":"https://access.redhat.com/security/cve/CVE-2026-53194"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/53xxx/CVE-2026-53194.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-53194"},{"type":"REPORT","url":"https://bugzilla.redhat.com/show_bug.cgi?id=2492703"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"60b3013cdaf3fa8a17243ca46b19db3cbe08d943"},{"fixed":"60af1fd82983c26604102e63a3fcc822c186cceb"},{"fixed":"0a57320f71941d4e0b1307453c9a1f0939afe666"},{"fixed":"14147b7963685957839c76ba8094924e22777d79"},{"fixed":"a1288cd700f721c1a119c4f1e8efa234e59caada"},{"fixed":"70d86e355c564b5510fde61361df014f5476c83e"},{"fixed":"372f33ebed747d91870f57c0a2e62884a870bffa"},{"fixed":"bde742b076cbe26ecc89c8c68c76ae076a524d02"},{"fixed":"96d47e40bf9db4a9efd5c8fb53287a508d165f14"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-53194.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"2.6.35"},{"fixed":"5.10.259"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"5.15.210"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.176"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.143"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.94"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.36"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.0.13"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-53194.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"}]}