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CVE-2021-43523

Estado: ModificadaCrítica (9.6)—

In uClibc and uClibc-ng before 1.0.39, incorrect handling of special characters in domain names returned by DNS servers via gethostbyname, getaddrinfo, gethostbyaddr, and getnameinfo can lead to output of wrong hostnames (leading to domain hijacking) or injection into applications (leading to remote code execution, XSS, applications crashes, etc.). In other words, a validation step, which is expected in any stub resolver, does not occur.

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 (2)

Uclibc — UclibcUclibc-ng Project — Uclibc-ng

CWE

Referencias

JSON original (NVD)

Mostrar
{
  "id": "CVE-2021-43523",
  "cveTags": [],
  "metrics": {
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2021-43523",
          "role": "CISA Coordinator",
          "options": [
            {
              "exploitation": "poc"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "version": "2.0.3",
          "timestamp": "2025-04-23T13:29:39.521750Z"
        }
      }
    ],
    "cvssMetricV2": [
      {
        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "version": "2.0",
          "baseScore": 6.8,
          "accessVector": "NETWORK",
          "vectorString": "AV:N/AC:M/Au:N/C:P/I:P/A:P",
          "authentication": "NONE",
          "integrityImpact": "PARTIAL",
          "accessComplexity": "MEDIUM",
          "availabilityImpact": "PARTIAL",
          "confidentialityImpact": "PARTIAL"
        },
        "acInsufInfo": false,
        "impactScore": 6.4,
        "baseSeverity": "MEDIUM",
        "obtainAllPrivilege": false,
        "exploitabilityScore": 8.6,
        "obtainUserPrivilege": false,
        "obtainOtherPrivilege": false,
        "userInteractionRequired": true
      }
    ],
    "cvssMetricV31": [
      {
        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "scope": "CHANGED",
          "version": "3.1",
          "baseScore": 9.6,
          "attackVector": "NETWORK",
          "baseSeverity": "CRITICAL",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H",
          "integrityImpact": "HIGH",
          "userInteraction": "REQUIRED",
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          "availabilityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "HIGH"
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        "exploitabilityScore": 2.8
      },
      {
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        "cvssData": {
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          "integrityImpact": "HIGH",
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          "confidentialityImpact": "HIGH"
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  "affected": [
    {
      "source": "cve@mitre.org",
      "affectedData": [
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          "vendor": "n/a",
          "product": "n/a",
          "versions": [
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  "published": "2021-11-10T15:15:12.213",
  "references": [
    {
      "url": "https://github.com/wbx-github/uclibc-ng/commit/0f822af0445e5348ce7b7bd8ce1204244f31d174",
      "tags": [
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      "source": "cve@mitre.org"
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      "url": "https://uclibc-ng.org/",
      "tags": [
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      "source": "cve@mitre.org"
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    {
      "url": "https://www.openwall.com/lists/oss-security/2021/11/09/1",
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      "url": "https://github.com/wbx-github/uclibc-ng/commit/0f822af0445e5348ce7b7bd8ce1204244f31d174",
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      "tags": [
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  "vulnStatus": "Modified",
  "weaknesses": [
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      "type": "Primary",
      "source": "nvd@nist.gov",
      "description": [
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          "value": "CWE-79"
        }
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    },
    {
      "type": "Secondary",
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "description": [
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          "lang": "en",
          "value": "CWE-79"
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  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "In uClibc and uClibc-ng before 1.0.39, incorrect handling of special characters in domain names returned by DNS servers via gethostbyname, getaddrinfo, gethostbyaddr, and getnameinfo can lead to output of wrong hostnames (leading to domain hijacking) or injection into applications (leading to remote code execution, XSS, applications crashes, etc.). In other words, a validation step, which is expected in any stub resolver, does not occur."
    },
    {
      "lang": "es",
      "value": "En uClibc y uClibc-ng versiones anteriores a 1.0.39, el manejo incorrecto de los caracteres especiales en los nombres de dominio devueltos por los servidores DNS por medio de gethostbyname, getaddrinfo, gethostbyaddr y getnameinfo puede conllevar a una salida de nombres de host erróneos (conllevando al secuestro de dominios) o una inyección en aplicaciones (conllevando a una ejecución de código remota, un ataque de tipo XSS, bloqueo de aplicaciones, etc.). En otras palabras, un paso de comprobación, que se espera en cualquier stub resolver, no ocurre"
    }
  ],
  "lastModified": "2026-06-17T04:11:04.027",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:uclibc:uclibc:*:*:*:*:*:*:*:*",
              "vulnerable": true,
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              "versionEndIncluding": "0.9.33.2"
            },
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              "vulnerable": true,
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              "versionEndExcluding": "1.0.39"
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          ],
          "operator": "OR"
        }
      ]
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  ],
  "sourceIdentifier": "cve@mitre.org"
}