ML-KEM (Kyber) decapsulation leaks private key information through non-constant-time division in message decoding and ciphertext compression (KyberSlash)

{
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "cveMetadata": {
    "cveId": "CVE-2024-14041",
    "assignerOrgId": "91579145-5d7b-4cc5-b925-a0262ff19630",
    "assignerShortName": "bcorg",
    "dateUpdated": "2026-07-28T12:55:43.574Z",
    "dateReserved": "2026-07-28T05:07:53.475Z",
    "datePublished": "2026-07-28T08:05:35.310Z",
    "state": "PUBLISHED"
  },
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        "shortName": "bcorg",
        "dateUpdated": "2026-07-28T08:05:35.310Z"
      },
      "title": "ML-KEM (Kyber) decapsulation leaks private key information through non-constant-time division in message decoding and ciphertext compression (KyberSlash)",
      "descriptions": [
        {
          "lang": "en",
          "value": "In Bouncy Castle for Java from 1.73 to before 1.78, three ML-KEM (CRYSTALS-Kyber) routines divided secret-derived polynomial coefficients by the modulus q: Poly.toMsg, which decodes the decrypted message, and the ciphertext compression routines Poly.compressPoly and PolyVec.compressPolyVec. An attacker able to measure the timing of a large number of decapsulations performed with the same long-term private key can recover that key. These are the KyberSlash1 (Poly.toMsg) and KyberSlash2 (ciphertext compression) divisions. Compression performed during encapsulation operates on values that become the public ciphertext and is not affected.",
          "supportingMedia": [
            {
              "type": "text/html",
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              "value": "<p>In Bouncy Castle for Java from 1.73 to before 1.78, three ML-KEM (CRYSTALS-Kyber) routines divided secret-derived polynomial coefficients by the modulus q: Poly.toMsg, which decodes the decrypted message, and the ciphertext compression routines Poly.compressPoly and PolyVec.compressPolyVec. An attacker able to measure the timing of a large number of decapsulations performed with the same long-term private key can recover that key. These are the KyberSlash1 (Poly.toMsg) and KyberSlash2 (ciphertext compression) divisions. Compression performed during encapsulation operates on values that become the public ciphertext and is not affected.</p>"
            }
          ]
        }
      ],
      "affected": [
        {
          "vendor": "Legion of the Bouncy Castle Inc.",
          "product": "BC-JAVA",
          "collectionURL": "https://www.bouncycastle.org/download/bouncy-castle-java/",
          "packageName": "bcprov",
          "modules": [
            "core"
          ],
          "programFiles": [
            "Poly",
            "PolyVec"
          ],
          "platforms": [
            "all"
          ],
          "repo": "https://github.com/bcgit/bc-java",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "1.73",
              "status": "affected",
              "versionType": "maven",
              "lessThan": "1.78"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "lang": "en",
              "description": "CWE-208 Observable Timing Discrepancy",
              "cweId": "CWE-208",
              "type": "CWE"
            }
          ]
        }
      ],
      "references": [
        {
          "url": "https://github.com/bcgit/bc-java/wiki/CVE-2024-14041",
          "tags": [
            "vendor-advisory"
          ]
        },
        {
          "url": "https://github.com/bcgit/bc-java/commit/5adb2c5c5b462a332b01a012bea0784b40b904e5",
          "tags": [
            "patch"
          ]
        },
        {
          "url": "https://github.com/bcgit/bc-java/commit/1590247178f2280defa36421475f015175dfbe9e",
          "tags": [
            "patch"
          ]
        },
        {
          "url": "https://kyberslash.cr.yp.to/",
          "tags": [
            "technical-description"
          ]
        }
      ],
      "metrics": [
        {
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
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      ],
      "credits": [
        {
          "lang": "en",
          "value": "The Robusta team: Deepak Pillai, Anirban Chakraborty, Chitchanok Chuengsatiansup, Matthew Roughan, Peter Schwabe and Yuval Yarom",
          "type": "finder"
        },
        {
          "lang": "en",
          "value": "The KyberSlash authors: Daniel J. Bernstein, Karthikeyan Bhargavan, Shivam Bhasin, Anupam Chattopadhyay, Tee Kiah Chia, Matthias J. Kannwischer, Franziskus Kiefer, Thales Paiva, Prasanna Ravi and Goutam Tamvada.",
          "type": "finder"
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    },
    "adp": [
      {
        "providerMetadata": {
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP",
          "dateUpdated": "2026-07-28T12:55:43.574Z"
        },
        "title": "CISA ADP Vulnrichment",
        "metrics": [
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