{"api_version":"1","generated_at":"2026-09-23T03:45:38+00:00","cve":"CVE-2026-89790","urls":{"html":"https://cve.report/CVE-2026-89790","api":"https://cve.report/api/cve/CVE-2026-89790.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-89790","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-89790"},"summary":{"title":"ipv6: avoid divide by zero in rt6_multipath_rebalance","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: avoid divide by zero in rt6_multipath_rebalance\n\nrt6_multipath_rebalance() calculates the total eligible nexthop weight\nin one pass and programs upper bounds in a second pass. Since\nRTM_NEWROUTE is RTNL-free, a concurrent\nignore_routes_with_linkdown update can make the first pass return zero\nwhile the second sees an eligible nexthop, causing\nrt6_upper_bound_set() to divide by zero.\n\nUBSAN: division-overflow in net/ipv6/route.c:4845:17\nOops: divide error: 0000 [#1] SMP KASAN NOPTI\n  rt6_upper_bound_set() net/ipv6/route.c:4845\n  rt6_multipath_rebalance()\n  fib6_add_rt2node()\n  ip6_route_multipath_add()\n  inet6_rtm_newroute()\n\nSkip upper-bound calculation when the first pass reports a zero total.\nThis respects the lock-free performance considerations here and solves\ninsecure scenarios.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-09-16 09:17:09","updated_at":"2026-09-16 09:17:09"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/f30cf8fd9872299c0c27f9916252ba2b9f422dce","name":"https://git.kernel.org/stable/c/f30cf8fd9872299c0c27f9916252ba2b9f422dce","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/d2c26c2911dd1a363c488add4fb63eb5f0f28f87","name":"https://git.kernel.org/stable/c/d2c26c2911dd1a363c488add4fb63eb5f0f28f87","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/f82b5dbb2fef65b52a62d5ffe05e0483c4385a83","name":"https://git.kernel.org/stable/c/f82b5dbb2fef65b52a62d5ffe05e0483c4385a83","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-89790","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89790","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected bd11ff421d36abdb585b9104fa70057bf01b3110 f30cf8fd9872299c0c27f9916252ba2b9f422dce git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected bd11ff421d36abdb585b9104fa70057bf01b3110 f82b5dbb2fef65b52a62d5ffe05e0483c4385a83 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected bd11ff421d36abdb585b9104fa70057bf01b3110 d2c26c2911dd1a363c488add4fb63eb5f0f28f87 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.16","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.16 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.52 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.6 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3-rc1 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["net/ipv6/route.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"f30cf8fd9872299c0c27f9916252ba2b9f422dce","status":"affected","version":"bd11ff421d36abdb585b9104fa70057bf01b3110","versionType":"git"},{"lessThan":"f82b5dbb2fef65b52a62d5ffe05e0483c4385a83","status":"affected","version":"bd11ff421d36abdb585b9104fa70057bf01b3110","versionType":"git"},{"lessThan":"d2c26c2911dd1a363c488add4fb63eb5f0f28f87","status":"affected","version":"bd11ff421d36abdb585b9104fa70057bf01b3110","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["net/ipv6/route.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"6.16"},{"lessThan":"6.16","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.52","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.6","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.3-rc1","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.52","versionStartIncluding":"6.16","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.6","versionStartIncluding":"6.16","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3-rc1","versionStartIncluding":"6.16","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: avoid divide by zero in rt6_multipath_rebalance\n\nrt6_multipath_rebalance() calculates the total eligible nexthop weight\nin one pass and programs upper bounds in a second pass. Since\nRTM_NEWROUTE is RTNL-free, a concurrent\nignore_routes_with_linkdown update can make the first pass return zero\nwhile the second sees an eligible nexthop, causing\nrt6_upper_bound_set() to divide by zero.\n\nUBSAN: division-overflow in net/ipv6/route.c:4845:17\nOops: divide error: 0000 [#1] SMP KASAN NOPTI\n  rt6_upper_bound_set() net/ipv6/route.c:4845\n  rt6_multipath_rebalance()\n  fib6_add_rt2node()\n  ip6_route_multipath_add()\n  inet6_rtm_newroute()\n\nSkip upper-bound calculation when the first pass reports a zero total.\nThis respects the lock-free performance considerations here and solves\ninsecure scenarios."}],"providerMetadata":{"dateUpdated":"2026-09-16T08:48:26.343Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/f30cf8fd9872299c0c27f9916252ba2b9f422dce"},{"url":"https://git.kernel.org/stable/c/f82b5dbb2fef65b52a62d5ffe05e0483c4385a83"},{"url":"https://git.kernel.org/stable/c/d2c26c2911dd1a363c488add4fb63eb5f0f28f87"}],"title":"ipv6: avoid divide by zero in rt6_multipath_rebalance","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-89790","datePublished":"2026-09-16T08:48:26.343Z","dateReserved":"2026-09-11T19:38:34.766Z","dateUpdated":"2026-09-16T08:48:26.343Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-16 09:17:09","lastModifiedDate":"2026-09-16 09:17:09","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"89790","Ordinal":"1","Title":"ipv6: avoid divide by zero in rt6_multipath_rebalance","CVE":"CVE-2026-89790","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"89790","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: avoid divide by zero in rt6_multipath_rebalance\n\nrt6_multipath_rebalance() calculates the total eligible nexthop weight\nin one pass and programs upper bounds in a second pass. Since\nRTM_NEWROUTE is RTNL-free, a concurrent\nignore_routes_with_linkdown update can make the first pass return zero\nwhile the second sees an eligible nexthop, causing\nrt6_upper_bound_set() to divide by zero.\n\nUBSAN: division-overflow in net/ipv6/route.c:4845:17\nOops: divide error: 0000 [#1] SMP KASAN NOPTI\n  rt6_upper_bound_set() net/ipv6/route.c:4845\n  rt6_multipath_rebalance()\n  fib6_add_rt2node()\n  ip6_route_multipath_add()\n  inet6_rtm_newroute()\n\nSkip upper-bound calculation when the first pass reports a zero total.\nThis respects the lock-free performance considerations here and solves\ninsecure scenarios.","Type":"Description","Title":"ipv6: avoid divide by zero in rt6_multipath_rebalance"}]}}}