{"id":"CVE-2026-68297","title":"tipc: fix u16 MTU truncation in media and bearer MTU validation","summary":"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 minimu…","severity":"high","cvss":7.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cvssSource":"cna","vendor":"Linux","product":"Linux","affected":["Linux >= 901271e0403af638c224987c2a4e55cebade7e91 < 8bfdfe0dbb36a650b7c4dec1aeae078319938a0b","Linux >= 901271e0403af638c224987c2a4e55cebade7e91 < dc4b577a083b361d25e118dc96d8281255ebe22c","Linux >= 901271e0403af638c224987c2a4e55cebade7e91 < dfdfd987f1917c84766e097a6120a1f3f1634940","Linux >= 901271e0403af638c224987c2a4e55cebade7e91 < f02334a9e378f7e07232b26dc3d2ab353339f040","Linux >= 901271e0403af638c224987c2a4e55cebade7e91 < f4013598b69457dbea350df52e52daea6faef8eb","Linux >= 901271e0403af638c224987c2a4e55cebade7e91 < 1b8fb5a20508bfb0db854e01214888c761b3a911","Linux >= 901271e0403af638c224987c2a4e55cebade7e91 < c1cda72f6acec02ebd45d913bf8527ff77336ba6","Linux >= 901271e0403af638c224987c2a4e55cebade7e91 < 9f29cd8a8e7901a2617c8064ce9f50fc67b97cb8","Linux 4.18"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"total","timestamp":"2026-10-16T15:46:47.440623Z"},"published":"2026-08-10","updated":"2026-10-16","sourceUpdated":"2026-10-16T15:53:06.926Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-68297","references":[{"url":"https://git.kernel.org/stable/c/8bfdfe0dbb36a650b7c4dec1aeae078319938a0b"},{"url":"https://git.kernel.org/stable/c/dc4b577a083b361d25e118dc96d8281255ebe22c"},{"url":"https://git.kernel.org/stable/c/dfdfd987f1917c84766e097a6120a1f3f1634940"},{"url":"https://git.kernel.org/stable/c/f02334a9e378f7e07232b26dc3d2ab353339f040"},{"url":"https://git.kernel.org/stable/c/f4013598b69457dbea350df52e52daea6faef8eb"},{"url":"https://git.kernel.org/stable/c/1b8fb5a20508bfb0db854e01214888c761b3a911"},{"url":"https://git.kernel.org/stable/c/c1cda72f6acec02ebd45d913bf8527ff77336ba6"},{"url":"https://git.kernel.org/stable/c/9f29cd8a8e7901a2617c8064ce9f50fc67b97cb8"}],"tags":["cve.org"],"epss":0.00129,"epssPercentile":0.02277,"ingestedAt":"2026-10-16T17:24:46.855Z","slug":"CVE-2026-68297","body":"## Overview\n\nIn 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->mtu and\nl->advertised_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->mtu / 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.\n\n## Affected\n\n- `Linux >= 901271e0403af638c224987c2a4e55cebade7e91 < 8bfdfe0dbb36a650b7c4dec1aeae078319938a0b`\n- `Linux >= 901271e0403af638c224987c2a4e55cebade7e91 < dc4b577a083b361d25e118dc96d8281255ebe22c`\n- `Linux >= 901271e0403af638c224987c2a4e55cebade7e91 < dfdfd987f1917c84766e097a6120a1f3f1634940`\n- `Linux >= 901271e0403af638c224987c2a4e55cebade7e91 < f02334a9e378f7e07232b26dc3d2ab353339f040`\n- `Linux >= 901271e0403af638c224987c2a4e55cebade7e91 < f4013598b69457dbea350df52e52daea6faef8eb`\n- `Linux >= 901271e0403af638c224987c2a4e55cebade7e91 < 1b8fb5a20508bfb0db854e01214888c761b3a911`\n- `Linux >= 901271e0403af638c224987c2a4e55cebade7e91 < c1cda72f6acec02ebd45d913bf8527ff77336ba6`\n- `Linux >= 901271e0403af638c224987c2a4e55cebade7e91 < 9f29cd8a8e7901a2617c8064ce9f50fc67b97cb8`\n- `Linux 4.18`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":43,"depthScoreParts":{"impact":42.9,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}