{"id":"CVE-2026-89631","summary":"smb: client: reject a tree connect response whose byte count is too small","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: reject a tree connect response whose byte count is too small\n\nCIFSTCon() bounds its strnlen() over the byte area with the server's\nByteCount minus two, which for ByteCount 0 or 1 goes negative as an int\nand converts to a huge size_t.  The later subtraction wraps the __u16\nbytes_left, and that is what bounds cifs_strndup_from_utf16(): a bound of\nup to 65535 against a ~16 KB cifs_req_poolp object runs off the end of the\nslab object, and the bytes reach userspace through tcon-\u003enativeFileSystem\nin /proc/fs/cifs/DebugData.\n\nReject a byte area too small for what the parser consumes.  Two bytes is\nthe least it can consume, and no conformant response carries fewer.  The\nnew trace point is the 129th smb_eio_trace entry, which __mode(byte)\ncannot represent, so the attribute goes with it.","modified":"2026-11-14T17:28:25.445522205Z","published":"2026-09-11T19:45:26.444Z","related":["ALSA-2026:85321","ALSA-2026:85773","ALSA-2026:85774","SUSE-SU-2026:24181-1","SUSE-SU-2026:24182-1","SUSE-SU-2026:24315-1","SUSE-SU-2026:24316-1","SUSE-SU-2026:24386-1","SUSE-SU-2026:24422-1","SUSE-SU-2026:24437-1","SUSE-SU-2026:24446-1","SUSE-SU-2026:4640-1","SUSE-SU-2026:4660-1","SUSE-SU-2026:4665-1","SUSE-SU-2026:4666-1","SUSE-SU-2026:4667-1","SUSE-SU-2026:4668-1","SUSE-SU-2026:4706-1","SUSE-SU-2026:5121-1","openSUSE-SU-2026:11880-1","openSUSE-SU-2026:22167-1","openSUSE-SU-2026:22309-1","openSUSE-SU-2026:22313-1"],"database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89631.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/2ae219762ebac929bf6ab3473681f10ed566af08"},{"type":"WEB","url":"https://git.kernel.org/stable/c/3be89e8039a85fa3b6cd5f9dcc4c1459eb356c2d"},{"type":"WEB","url":"https://git.kernel.org/stable/c/411e484fe71a7f1028de617447edad9cb6d9d68a"},{"type":"WEB","url":"https://git.kernel.org/stable/c/65deb18359341141d37dc86fc7853511be3c87a7"},{"type":"WEB","url":"https://git.kernel.org/stable/c/bb99866cb1d3d5e8201200a8692fd8da3106a8fd"},{"type":"WEB","url":"https://git.kernel.org/stable/c/d837645a719151ed392d4d9cab4571c2753dab12"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89631.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89631"},{"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":"cc20c031bb067eb3280a1c4b5c42295093e24863"},{"fixed":"bb99866cb1d3d5e8201200a8692fd8da3106a8fd"},{"fixed":"d837645a719151ed392d4d9cab4571c2753dab12"},{"fixed":"2ae219762ebac929bf6ab3473681f10ed566af08"},{"fixed":"3be89e8039a85fa3b6cd5f9dcc4c1459eb356c2d"},{"fixed":"411e484fe71a7f1028de617447edad9cb6d9d68a"},{"fixed":"65deb18359341141d37dc86fc7853511be3c87a7"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-89631.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"2.6.30"},{"fixed":"6.1.191"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.160"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.114"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.51"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.2.4"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-89631.json"}}],"schema_version":"1.9.2","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H"}]}