CVE-2008-4066

Status: ModifiedMedium (4.3)—
Mozilla Firefox 2.0.0.14, and other versions before 2.0.0.17, allows remote attackers to bypass cross-site scripting (XSS) protection mechanisms and conduct XSS attacks via HTML-escaped low surrogate characters that are ignored by the HTML parser, as demonstrated by a "jav&#56325ascript" sequence, aka "HTML escaped low surrogates bug."
CVSS

Version: 2.0
Vector: AV:N/AC:M/Au:N/C:N/I:P/A:N
Base score: 4.3
Exploitation probability (EPSS)

Probability of exploitation in the next 30 days: 1.76%
Percentile among all scored CVEs: 78
Score date: 10/14/2026
EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).
Affected technologies (1)

Mozilla — Firefox
CWEs

CWE-79
References

Raw JSON (NVD)

Show
{
  "id": "CVE-2008-4066",
  "cveTags": [],
  "metrics": {
    "cvssMetricV2": [
      {
        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "version": "2.0",
          "baseScore": 4.3,
          "accessVector": "NETWORK",
          "vectorString": "AV:N/AC:M/Au:N/C:N/I:P/A:N",
          "authentication": "NONE",
          "integrityImpact": "PARTIAL",
          "accessComplexity": "MEDIUM",
          "availabilityImpact": "NONE",
          "confidentialityImpact": "NONE"
        },
        "acInsufInfo": false,
        "impactScore": 2.9,
        "baseSeverity": "MEDIUM",
        "obtainAllPrivilege": false,
        "exploitabilityScore": 8.6,
        "obtainUserPrivilege": false,
        "obtainOtherPrivilege": false,
        "userInteractionRequired": true
      }
    ]
  },
  "affected": [
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      "affectedData": [
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          "product": "n/a",
          "versions": [
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              "version": "n/a"
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  "published": "2008-09-24T20:37:04.737",
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  ],
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "type": "Primary",
      "source": "nvd@nist.gov",
      "description": [
        {
          "lang": "en",
          "value": "CWE-79"
        }
      ]
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  "descriptions": [
    {
      "lang": "en",
      "value": "Mozilla Firefox 2.0.0.14, and other versions before 2.0.0.17, allows remote attackers to bypass cross-site scripting (XSS) protection mechanisms and conduct XSS attacks via HTML-escaped low surrogate characters that are ignored by the HTML parser, as demonstrated by a \"jav&#56325ascript\" sequence, aka \"HTML escaped low surrogates bug.\""
    },
    {
      "lang": "es",
      "value": "Mozilla Firefox versión 2.0.0.14, y otras versiones anteriores a 2.0.0.17, permiten a los atacantes remotos omitir los mecanismos de protección de cross-site scripting (XSS) y conducir ataques de tipo XSS por medio de caracteres sustitutos bajos con escape de HTML que son ignorados por el analizador HTML, como es demostrado por una secuencia \"jav?ascript\", también se conoce como \"HTML escaped low surrogates bug.\""
    }
  ],
  "lastModified": "2026-06-16T22:57:06.200",
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        {
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}