{"api_version":"1","generated_at":"2026-08-15T02:49:12+00:00","cve":"CVE-2026-68297","urls":{"html":"https://cve.report/CVE-2026-68297","api":"https://cve.report/api/cve/CVE-2026-68297.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-68297","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-68297"},"summary":{"title":"tipc: fix u16 MTU truncation in media and bearer MTU validation","description":"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->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.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-08-10 13:20:19","updated_at":"2026-08-13 23:17:28"},"problem_types":[],"metrics":[{"version":"3.1","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","score":"7.8","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","data":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"}},{"version":"3.1","source":"CNA","type":"DECLARED","score":"7.8","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","data":{"baseScore":7.8,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"}}],"references":[{"url":"https://git.kernel.org/stable/c/f4013598b69457dbea350df52e52daea6faef8eb","name":"https://git.kernel.org/stable/c/f4013598b69457dbea350df52e52daea6faef8eb","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/9f29cd8a8e7901a2617c8064ce9f50fc67b97cb8","name":"https://git.kernel.org/stable/c/9f29cd8a8e7901a2617c8064ce9f50fc67b97cb8","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/c1cda72f6acec02ebd45d913bf8527ff77336ba6","name":"https://git.kernel.org/stable/c/c1cda72f6acec02ebd45d913bf8527ff77336ba6","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/1b8fb5a20508bfb0db854e01214888c761b3a911","name":"https://git.kernel.org/stable/c/1b8fb5a20508bfb0db854e01214888c761b3a911","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/f02334a9e378f7e07232b26dc3d2ab353339f040","name":"https://git.kernel.org/stable/c/f02334a9e378f7e07232b26dc3d2ab353339f040","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-68297","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-68297","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 901271e0403af638c224987c2a4e55cebade7e91 f02334a9e378f7e07232b26dc3d2ab353339f040 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 901271e0403af638c224987c2a4e55cebade7e91 f4013598b69457dbea350df52e52daea6faef8eb git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 901271e0403af638c224987c2a4e55cebade7e91 1b8fb5a20508bfb0db854e01214888c761b3a911 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 901271e0403af638c224987c2a4e55cebade7e91 c1cda72f6acec02ebd45d913bf8527ff77336ba6 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 901271e0403af638c224987c2a4e55cebade7e91 9f29cd8a8e7901a2617c8064ce9f50fc67b97cb8 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4.18","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 4.18 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.6.148 6.6.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.101 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.42 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.1.6 7.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2-rc5 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"68297","cve":"CVE-2026-68297","epss":"0.001280000","percentile":"0.029120000","score_date":"2026-08-14","updated_at":"2026-08-15 00:04:44"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["net/tipc/netlink.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"f02334a9e378f7e07232b26dc3d2ab353339f040","status":"affected","version":"901271e0403af638c224987c2a4e55cebade7e91","versionType":"git"},{"lessThan":"f4013598b69457dbea350df52e52daea6faef8eb","status":"affected","version":"901271e0403af638c224987c2a4e55cebade7e91","versionType":"git"},{"lessThan":"1b8fb5a20508bfb0db854e01214888c761b3a911","status":"affected","version":"901271e0403af638c224987c2a4e55cebade7e91","versionType":"git"},{"lessThan":"c1cda72f6acec02ebd45d913bf8527ff77336ba6","status":"affected","version":"901271e0403af638c224987c2a4e55cebade7e91","versionType":"git"},{"lessThan":"9f29cd8a8e7901a2617c8064ce9f50fc67b97cb8","status":"affected","version":"901271e0403af638c224987c2a4e55cebade7e91","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["net/tipc/netlink.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"4.18"},{"lessThan":"4.18","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.6.*","status":"unaffected","version":"6.6.148","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.101","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.42","versionType":"semver"},{"lessThanOrEqual":"7.1.*","status":"unaffected","version":"7.1.6","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.2-rc5","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.6.148","versionStartIncluding":"4.18","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.101","versionStartIncluding":"4.18","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.42","versionStartIncluding":"4.18","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.1.6","versionStartIncluding":"4.18","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2-rc5","versionStartIncluding":"4.18","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"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->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."}],"metrics":[{"cvssV3_1":{"baseScore":7.8,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"},"scenarios":[{"lang":"en","value":"AV:L - The attack begins with a local TIPC netlink command (TIPC_NL_BEARER_SET/TIPC_NL_MEDIA_SET) setting an out-of-range MTU, with the crash/corruption then triggered by locally generated discovery traffic and sendmsg() in the attacker's own network namespace.\nAC:L - The attacker fully controls both the bad MTU value and the discovery packet that creates the link, so the truncation and subsequent divide-by-zero or undersized-fragment path trigger deterministically on every attempt.\nPR:L - Both netlink ops are gated by GENL_UNS_ADMIN_PERM, i.e. CAP_NET_ADMIN in the owning user namespace, which any unprivileged user obtains via `unshare -Urn`; the commit message explicitly reports the crash reproduced as an unprivileged user through a user namespace.\nUI:N - The attacker performs every step (bearer setup, MTU configuration, packet injection, sendmsg) with no action from any other user or administrator.\nS:U - The truncated MTU corrupts only kernel state within the same kernel security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - Truncated MTUs below the TIPC header size propagate into tipc_msg_build() as pktmax, driving negative fragment remainders and oversized copies into undersized skbs; the resulting heap corruption and adjacent-object exposure can be leveraged to read kernel memory.\nI:H - The undersized-fragment path writes INT_H_SIZE plus header bytes and then a negative-length (huge unsigned) user copy into a buffer allocated at the truncated MTU size, giving an attacker-controlled linear heap overflow suitable for control-flow hijacking.\nA:H - MTU values truncating to under 20 make tipc_link_set_queue_limits() divide by zero inside tipc_link_create(), which runs in softirq context from tipc_udp_recv()/tipc_disc_rcv(), producing a kernel oops that is typically fatal in interrupt context."}]}],"providerMetadata":{"dateUpdated":"2026-08-13T22:43:00.737Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"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"}],"title":"tipc: fix u16 MTU truncation in media and bearer MTU validation","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-68297","datePublished":"2026-08-10T12:02:30.721Z","dateReserved":"2026-07-30T09:28:09.380Z","dateUpdated":"2026-08-13T22:43:00.737Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-08-10 13:20:19","lastModifiedDate":"2026-08-13 23:17:28","problem_types":[],"metrics":{"cvssMetricV31":[{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":1.8,"impactScore":5.9}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"68297","Ordinal":"1","Title":"tipc: fix u16 MTU truncation in media and bearer MTU validation","CVE":"CVE-2026-68297","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"68297","Ordinal":"1","NoteData":"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->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.","Type":"Description","Title":"tipc: fix u16 MTU truncation in media and bearer MTU validation"}]}}}