{"schema":"threatline.record/2","record":{"id":"CVE-2026-99121","aliases":[],"summary":"ipv4: avoid divide by zero in fib_rebalance","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nipv4: avoid divide by zero in fib_rebalance\n\nfib_rebalance() computes the total eligible nexthop weight in one pass\nand programs upper bounds in a second pass. A concurrent change to\nignore_routes_with_linkdown can make the first pass return zero while\nthe second pass sees an eligible nexthop, resulting in division by zero.\n\nIf the first pass reports a zero total, set each nexthop upper bound to\n-1 and skip the division. This matches the IPv6 fix in commit\nd2c26c2911dd (\"ipv6: avoid divide by zero in rt6_multipath_rebalance\")\nand preserves the lock-free rebalance path.","categories":["Operating systems"],"product":"Linux","vendor":"Linux","ecosystem":null,"affected_ranges":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-99121","source_modified_at":"2026-10-28T10:34:37.082Z","fetched_at":"2026-10-28T15:55:58.673066Z","product":"Linux","vendor":"Linux","versions":[{"version":"0e884c78ee19e902f300ed147083c28a0c6302f0","lessThan":"5dac5c7ba8f5f3fb4bf29f2a2c3cb552f5b83c8f","status":"affected","versionType":"git"},{"version":"0e884c78ee19e902f300ed147083c28a0c6302f0","lessThan":"d5520e815c4b1427104ce1428ee23821f2aa824d","status":"affected","versionType":"git"},{"version":"0e884c78ee19e902f300ed147083c28a0c6302f0","lessThan":"5046d2880fec7d49ebed2fd2866747ee1d06ad71","status":"affected","versionType":"git"}],"defaultStatus":"unaffected"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-99121","source_modified_at":"2026-10-28T10:34:37.082Z","fetched_at":"2026-10-28T15:55:58.673066Z","product":"Linux","vendor":"Linux","versions":[{"version":"4.4","status":"affected"},{"version":"0","lessThan":"4.4","status":"unaffected","versionType":"semver"},{"version":"6.18.59","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.2.13","lessThanOrEqual":"7.2.*","status":"unaffected","versionType":"semver"},{"version":"7.3","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}],"defaultStatus":"affected"}],"fixed_versions":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-99121","source_modified_at":"2026-10-28T10:34:37.082Z","fetched_at":"2026-10-28T15:55:58.673066Z","package":{"name":"Linux","ecosystem":null},"version":"5dac5c7ba8f5f3fb4bf29f2a2c3cb552f5b83c8f","basis":"first unaffected version stated in the CVE record"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-99121","source_modified_at":"2026-10-28T10:34:37.082Z","fetched_at":"2026-10-28T15:55:58.673066Z","package":{"name":"Linux","ecosystem":null},"version":"5046d2880fec7d49ebed2fd2866747ee1d06ad71","basis":"first unaffected version stated in the CVE record"}],"cvss":null,"severity":null,"kev":{"listed":false},"epss":{"probability":null,"percentile":null,"score_date":null},"published_at":"2026-10-28T10:34:37.082Z","modified_at":"2026-10-28T10:34:37.082Z","provenance":[{"source":"CVE List","url":"https://www.cve.org/CVERecord?id=CVE-2026-99121","fetched_at":"2026-10-28T15:55:58.673066Z","source_modified_at":"2026-10-28T10:34:37.082Z"}],"sources":["CVE List"],"references":[{"source":"CVE List","url":"https://git.kernel.org/stable/c/5dac5c7ba8f5f3fb4bf29f2a2c3cb552f5b83c8f"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/d5520e815c4b1427104ce1428ee23821f2aa824d"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/5046d2880fec7d49ebed2fd2866747ee1d06ad71"}],"locations":[],"motoko_assessment":{"status":"requires_architecture_review","automatic_remediation":false},"cve_state":"PUBLISHED","classification":{"method":"product-first software-layer rules","rules_version":"2.1","matched_on":"product","confidence":"heuristic","reviewed":false},"change_timestamp":"2026-10-28T10:34:37.082Z","content_hash":"fc8ac1c7e8d5646d1ebb1c33765590f073f7a050cdf5ca6a1ac2ace4f4082645"}}