{"id":"CVE-2026-68297","summary":"tipc: fix u16 MTU truncation in media and bearer MTU validation","details":"In the Linux kernel, the following vulnerability has been resolved:\n\ntipc: fix u16 MTU truncation in media and bearer MTU validation\n\nBoth TIPC_NL_MEDIA_SET and TIPC_NL_BEARER_SET accept user-supplied\nMTU values but only enforce a minimum bound, not a maximum. When a user\nsets the MTU to a value exceeding U16_MAX (65535), it passes validation\nbut is silently truncated when assigned to u16 fields l-\u003emtu and\nl-\u003eadvertised_mtu in tipc_link_create(). Values like 65536 (0x10000)\ntruncate to 0, causing a division by zero in tipc_link_set_queue_limits()\nwhich computes TIPC_MAX_PUBL / (l-\u003emtu / ITEM_SIZE). Other overflowing\nvalues (e.g. 65537-131071) produce small incorrect MTU values, resulting\nin link malfunction behaviors.\n\nCrash stack (triggered as unprivileged user via user namespace):\n\n  tipc_link_set_queue_limits  net/tipc/link.c:2531\n  tipc_link_create            net/tipc/link.c:520\n  tipc_node_check_dest        net/tipc/node.c:1279\n  tipc_disc_rcv               net/tipc/discover.c:252\n  tipc_rcv                    net/tipc/node.c:2129\n  tipc_udp_recv               net/tipc/udp_media.c:392\n\nTwo independent paths lack the upper bound check:\n1. tipc_udp_mtu_bad() -- called from __tipc_nl_media_set() (MEDIA_SET)\n2. inline check in __tipc_nl_bearer_set() at bearer.c:1160 (BEARER_SET)\n\nFix both by rejecting MTU values above U16_MAX.","modified":"2026-08-21T03:30:46.479853200Z","published":"2026-08-10T12:02:30.721Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/68xxx/CVE-2026-68297.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/1b8fb5a20508bfb0db854e01214888c761b3a911"},{"type":"WEB","url":"https://git.kernel.org/stable/c/8bfdfe0dbb36a650b7c4dec1aeae078319938a0b"},{"type":"WEB","url":"https://git.kernel.org/stable/c/9f29cd8a8e7901a2617c8064ce9f50fc67b97cb8"},{"type":"WEB","url":"https://git.kernel.org/stable/c/c1cda72f6acec02ebd45d913bf8527ff77336ba6"},{"type":"WEB","url":"https://git.kernel.org/stable/c/dc4b577a083b361d25e118dc96d8281255ebe22c"},{"type":"WEB","url":"https://git.kernel.org/stable/c/dfdfd987f1917c84766e097a6120a1f3f1634940"},{"type":"WEB","url":"https://git.kernel.org/stable/c/f02334a9e378f7e07232b26dc3d2ab353339f040"},{"type":"WEB","url":"https://git.kernel.org/stable/c/f4013598b69457dbea350df52e52daea6faef8eb"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/68xxx/CVE-2026-68297.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-68297"},{"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":"901271e0403af638c224987c2a4e55cebade7e91"},{"fixed":"8bfdfe0dbb36a650b7c4dec1aeae078319938a0b"},{"fixed":"dc4b577a083b361d25e118dc96d8281255ebe22c"},{"fixed":"dfdfd987f1917c84766e097a6120a1f3f1634940"},{"fixed":"f02334a9e378f7e07232b26dc3d2ab353339f040"},{"fixed":"f4013598b69457dbea350df52e52daea6faef8eb"},{"fixed":"1b8fb5a20508bfb0db854e01214888c761b3a911"},{"fixed":"c1cda72f6acec02ebd45d913bf8527ff77336ba6"},{"fixed":"9f29cd8a8e7901a2617c8064ce9f50fc67b97cb8"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-68297.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"4.18.0"},{"fixed":"5.10.265"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"5.15.216"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.183"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.148"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.101"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.42"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.1.6"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-68297.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"}]}