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CVE-2026-87080

Estado: AplazadaCrítica (9.1)—

Net::IDN::Punycode::PP versions before 2.590 for Perl decode a truncated label to a name containing a character it never encoded in decode_punycode.

The pure-Perl decoder reads one digit at a time with four-argument substr and tests the result with defined to detect the end of the input. substr on an exhausted string returns the empty string rather than undef, so decoding continues past the end. The empty string converts to a digit value below the range, reducing the accumulator, and the decoder derives one extra code point and its position from it. The result is deterministic. The XS backend rejects the same label.

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Net::IDN::Punycode uses this backend wherever the XS does not build.

The two backends disagree about what such a label means, so a sender can pick a label that one installation resolves to a name and another rejects.

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).

🎯 Técnicas ATT&CK

Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.

Vulnerabilidad de decodificación en librería Perl expuesta en red (AV:N, PR:N). Genera divergencia entre backends permitiendo nombres DNS malformados que un servidor acepta pero otro rechaza, facilitando suplantación de dominio.

Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.

🛡️ Mitigaciones ATT&CK que cubren estas técnicas

Vulnerability ScanningPrivileged Account ManagementNetwork SegmentationLimit Access to Resource Over NetworkFilter Network TrafficApplication Isolation and Sandboxing

Tecnologías afectadas (1)

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

NET — IDN Punycode PPAI

CWE

Referencias

JSON original (NVD)

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{
  "id": "CVE-2026-87080",
  "cveTags": [],
  "metrics": {
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-87080",
          "role": "CISA Coordinator",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "version": "2.0.3",
          "timestamp": "2026-09-22T15:22:56.999361Z"
        }
      }
    ],
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 9.1,
          "attackVector": "NETWORK",
          "baseSeverity": "CRITICAL",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H",
          "integrityImpact": "NONE",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "HIGH"
        },
        "impactScore": 5.2,
        "exploitabilityScore": 3.9
      }
    ]
  },
  "affected": [
    {
      "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
      "affectedData": [
        {
          "repo": "https://github.com/robrwo/Net-IDN-Encode",
          "modules": [
            "Net::IDN::Punycode::PP"
          ],
          "versions": [
            {
              "status": "affected",
              "version": "0",
              "lessThan": "2.590",
              "versionType": "custom"
            }
          ],
          "packageURL": "pkg:cpan/Net-IDN-Encode",
          "packageName": "Net-IDN-Encode",
          "programFiles": [
            "lib/Net/IDN/Punycode/PP.pm"
          ],
          "collectionURL": "https://cpan.org/modules",
          "defaultStatus": "unaffected",
          "programRoutines": [
            {
              "name": "Net::IDN::Punycode::PP::decode_punycode"
            }
          ]
        }
      ]
    }
  ],
  "published": "2026-09-22T08:16:40.750",
  "references": [
    {
      "url": "https://github.com/robrwo/Net-IDN-Encode/commit/48436c7ad2c4d4c6398110e11133754fc476a783.patch",
      "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e"
    },
    {
      "url": "https://metacpan.org/release/PJCJ/Net-IDN-Encode-2.590-TRIAL/changes",
      "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e"
    },
    {
      "url": "http://www.openwall.com/lists/oss-security/2026/09/22/15",
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    }
  ],
  "vulnStatus": "Deferred",
  "weaknesses": [
    {
      "type": "Secondary",
      "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
      "description": [
        {
          "lang": "en",
          "value": "CWE-1286"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "Net::IDN::Punycode::PP versions before 2.590 for Perl decode a truncated label to a name containing a character it never encoded in decode_punycode.\n\nThe pure-Perl decoder reads one digit at a time with four-argument substr and tests the result with defined to detect the end of the input. substr on an exhausted string returns the empty string rather than undef, so decoding continues past the end. The empty string converts to a digit value below the range, reducing the accumulator, and the decoder derives one extra code point and its position from it. The result is deterministic. The XS backend rejects the same label.\n\nNet::IDN::Punycode uses this backend wherever the XS does not build.\n\nThe two backends disagree about what such a label means, so a sender can pick a label that one installation resolves to a name and another rejects."
    }
  ],
  "lastModified": "2026-09-22T19:07:00.983",
  "sourceIdentifier": "9b29abf9-4ab0-4765-b253-1875cd9b441e"
}