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CVE-2026-57082

Estado: AplazadaMedia (5.9)—

Net::BitTorrent versions before 2.1.0 for Perl generate the MSE Diffie-Hellman private key with a non-cryptographic PRNG.

The MSE (Message Stream Encryption) handshake derives its 160-bit Diffie-Hellman private key from Perl's rand(), a non-cryptographic drand48-class generator seeded once per process, in KeyExchange.pm. The shared secret and the RC4 keys derived from it (the SHA-1 of "keyA" or "keyB", the shared secret, and the infohash) therefore depend entirely on a predictable PRNG. The same handshake sends, in cleartext, random padding drawn from the same rand() sequence in _random_pad, immediately after the public key and the private-key draw.

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A passive observer of the handshake recovers the PRNG state from the cleartext padding, reconstructs the private key, computes the shared secret from the peer's public key on the wire, derives the RC4 keys, and decrypts the connection, defeating the passive-observation obfuscation MSE provides.

CVSS

Probabilidad de explotación (EPSS)

EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).

Tecnologías afectadas (1)

⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.

NET Bittorrent — NET BittorrentAI

CWE

Referencias

JSON original (NVD)

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{
  "id": "CVE-2026-57082",
  "cveTags": [],
  "metrics": {
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-57082",
          "role": "CISA Coordinator",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "version": "2.0.3",
          "timestamp": "2026-06-30T14:19:46.278267Z"
        }
      }
    ],
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 5.9,
          "attackVector": "NETWORK",
          "baseSeverity": "MEDIUM",
          "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N",
          "integrityImpact": "NONE",
          "userInteraction": "NONE",
          "attackComplexity": "HIGH",
          "availabilityImpact": "NONE",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "HIGH"
        },
        "impactScore": 3.6,
        "exploitabilityScore": 2.2
      }
    ]
  },
  "affected": [
    {
      "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
      "affectedData": [
        {
          "repo": "https://github.com/sanko/Net-BitTorrent.pm",
          "vendor": "SANKO",
          "product": "Net::BitTorrent",
          "versions": [
            {
              "status": "affected",
              "version": "0",
              "lessThan": "2.1.0",
              "versionType": "custom"
            }
          ],
          "packageName": "Net-BitTorrent",
          "programFiles": [
            "lib/Net/BitTorrent/Protocol/MSE/KeyExchange.pm",
            "lib/Net/BitTorrent/Protocol/MSE.pm",
            "lib/Net/BitTorrent/Peer.pm"
          ],
          "collectionURL": "https://cpan.org/modules",
          "defaultStatus": "unaffected",
          "programRoutines": [
            {
              "name": "Net::BitTorrent::Protocol::MSE::_random_pad"
            }
          ]
        }
      ]
    }
  ],
  "published": "2026-06-30T12:16:25.737",
  "references": [
    {
      "url": "https://github.com/sanko/Net-BitTorrent.pm/security/advisories/GHSA-g444-x2c5-94hc",
      "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e"
    },
    {
      "url": "https://metacpan.org/release/SANKO/Net-BitTorrent-v2.1.0/changes",
      "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e"
    }
  ],
  "vulnStatus": "Deferred",
  "weaknesses": [
    {
      "type": "Secondary",
      "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
      "description": [
        {
          "lang": "en",
          "value": "CWE-330"
        },
        {
          "lang": "en",
          "value": "CWE-338"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "Net::BitTorrent versions before 2.1.0 for Perl generate the MSE Diffie-Hellman private key with a non-cryptographic PRNG.\n\nThe MSE (Message Stream Encryption) handshake derives its 160-bit Diffie-Hellman private key from Perl's rand(), a non-cryptographic drand48-class generator seeded once per process, in KeyExchange.pm. The shared secret and the RC4 keys derived from it (the SHA-1 of \"keyA\" or \"keyB\", the shared secret, and the infohash) therefore depend entirely on a predictable PRNG. The same handshake sends, in cleartext, random padding drawn from the same rand() sequence in _random_pad, immediately after the public key and the private-key draw.\n\nA passive observer of the handshake recovers the PRNG state from the cleartext padding, reconstructs the private key, computes the shared secret from the peer's public key on the wire, derives the RC4 keys, and decrypts the connection, defeating the passive-observation obfuscation MSE provides."
    }
  ],
  "lastModified": "2026-07-20T07:16:39.517",
  "sourceIdentifier": "9b29abf9-4ab0-4765-b253-1875cd9b441e"
}