{
  "cveId": "CVE-2026-18036",
  "url": "https://patchblox.com/security/cve/CVE-2026-18036",
  "summary": "CVE-2026-18036 is fixed in bouncycastle on 1 platform, first by DEBIAN-CVE-2026-18036, released October 3, 2026. It is not reported as exploited. Patch Radar priority: Routine.",
  "title": "bouncycastle: In Bouncy Castle for Java before 1.86, NTRU reduced secret values with the % operator in three helpers whose referenc...",
  "description": "In Bouncy Castle for Java before 1.86, NTRU reduced secret values with the % operator in three helpers whose reference implementations are deliberately division-free, so each reduction was carried out by an integer division whose latency depends on the secret operand. Polynomial.modQ divided by a variable divisor, which a compiler cannot strength-reduce to a multiply the way it can a constant one, so it emitted a division on every call including on the decapsulation path where the dividend derives from the private key; Polynomial.mod3 and NTRUSampling.mod3 divided the secret key polynomials f and g during key generation, the message polynomials r and m during encapsulation, and coefficients recovered during decapsulation. An attacker able to measure that timing can recover information about the NTRU private key. modQ now masks, which is exact because q is always a power of two, and mod3 uses the reference implementation\u0027s division-free fold and select; the results are unchanged.",
  "published": "2026-10-02T08:17:01Z",
  "severity": "",
  "epss": 0.00282,
  "epssPercentile": 0.20868,
  "priority": "Routine",
  "priorityTier": 4,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "fixes": [
    {
      "platform": "linux",
      "product": "bouncycastle",
      "release": "Debian 14",
      "fixedVersion": "1.86-1",
      "fix": "DEBIAN-CVE-2026-18036",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-18036",
      "released": "2026-10-03T21:16:35Z"
    },
    {
      "platform": "linux",
      "product": "bouncycastle",
      "release": "opensuse-leap 16.0",
      "fixedVersion": "1.86-160000.1.1",
      "fix": "OPENSUSE-SU-2026:22169-1",
      "url": "https://patchblox.com/security/fix/linux/opensuse-su-2026-22169-1",
      "released": "2026-11-07T00:47:19Z"
    },
    {
      "platform": "linux",
      "product": "bouncycastle",
      "release": "sles 15.6",
      "fixedVersion": "1.86-150200.3.41.1",
      "fix": "SUSE-SU-2026:4797-1",
      "url": "https://patchblox.com/security/fix/linux/suse-su-2026-4797-1",
      "released": "2026-11-07T00:42:08Z"
    },
    {
      "platform": "linux",
      "product": "bouncycastle",
      "release": "sles 15.7",
      "fixedVersion": "1.86-150200.3.41.1",
      "fix": "SUSE-SU-2026:4797-1",
      "url": "https://patchblox.com/security/fix/linux/suse-su-2026-4797-1",
      "released": "2026-11-07T00:42:08Z"
    },
    {
      "platform": "linux",
      "product": "bouncycastle",
      "release": "sles 16.0",
      "fixedVersion": "1.86-160000.1.1",
      "fix": "SUSE-SU-2026:24461-1",
      "url": "https://patchblox.com/security/fix/linux/suse-su-2026-24461-1",
      "released": "2026-11-07T00:44:01Z"
    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-09T01:18:40Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}