{"id":"CVE-2026-99121","revision":"5cdff681fb4c43779f162503d3a1f186","records":[{"revision":"5cdff681fb4c43779f162503d3a1f186","observedAt":"2026-10-28T11:27:43.363+00:00","statement":{"source":"cve-program","id":"CVE-2026-99121","aliases":[],"title":"ipv4: avoid divide by zero in fib_rebalance","description":"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.","state":0,"publishedAt":"2026-10-28T10:34:37.082+00:00","modifiedAt":"2026-10-28T10:34:37.082+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"unaffected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"net/ipv4/fib_semantics.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"0e884c78ee19e902f300ed147083c28a0c6302f0\",\n                            \"lessThan\": \"5dac5c7ba8f5f3fb4bf29f2a2c3cb552f5b83c8f\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"0e884c78ee19e902f300ed147083c28a0c6302f0\",\n                            \"lessThan\": \"d5520e815c4b1427104ce1428ee23821f2aa824d\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"0e884c78ee19e902f300ed147083c28a0c6302f0\",\n                            \"lessThan\": \"5046d2880fec7d49ebed2fd2866747ee1d06ad71\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        }\n                    ]\n                }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"affected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"net/ipv4/fib_semantics.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"4.4\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \"0\",\n                            \"lessThan\": \"4.4\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.18.59\",\n                            \"lessThanOrEqual\": \"6.18.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.2.13\",\n                            \"lessThanOrEqual\": \"7.2.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.3\",\n                            \"lessThanOrEqual\": \"*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"original_commit_for_fix\"\n                        }\n                    ]\n                }"}],"metrics":[],"references":["https://git.kernel.org/stable/c/5dac5c7ba8f5f3fb4bf29f2a2c3cb552f5b83c8f","https://git.kernel.org/stable/c/d5520e815c4b1427104ce1428ee23821f2aa824d","https://git.kernel.org/stable/c/5046d2880fec7d49ebed2fd2866747ee1d06ad71"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-99121","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-99121","identifiers":["CVE-2026-99121"]},"retained":false,"historicalAffected":[]}],"coverage":[]}