{
  "cveId": "CVE-2026-99121",
  "url": "https://patchblox.com/security/cve/CVE-2026-99121",
  "summary": "CVE-2026-99121 is fixed in linux on 1 platform, first by DEBIAN-CVE-2026-99121, released November 3, 2026. It is not reported as exploited. Patch Radar priority: Routine.",
  "title": "ipv4: avoid divide by zero in fib_rebalance",
  "description": "In the Linux kernel, the following vulnerability has been resolved:  ipv4: avoid divide by zero in fib_rebalance  fib_rebalance() computes the total eligible nexthop weight in one pass and programs upper bounds in a second pass. A concurrent change to ignore_routes_with_linkdown can make the first pass return zero while the second pass sees an eligible nexthop, resulting in division by zero.  If the first pass reports a zero total, set each nexthop upper bound to -1 and skip the division. This matches the IPv6 fix in commit d2c26c2911dd (\u0022ipv6: avoid divide by zero in rt6_multipath_rebalance\u0022) and preserves the lock-free rebalance path.",
  "published": "2026-10-28T11:17:31Z",
  "severity": "Moderate",
  "cvss": 4.1,
  "epss": 0.00185,
  "epssPercentile": 0.08158,
  "priority": "Routine",
  "priorityTier": 4,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "vendorAdvisory": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-99121",
  "fixes": [
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 13.5 (trixie)",
      "fixedVersion": "6.12.115-2",
      "fix": "DEBIAN-CVE-2026-99121",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-99121",
      "released": "2026-11-03T18:58:21Z"
    },
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 14",
      "fixedVersion": "7.2.13-1",
      "fix": "DEBIAN-CVE-2026-99121",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-99121",
      "released": "2026-11-03T18:58:21Z"
    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-08T06:59:42Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}