GHSA-C486-5FVQ-FP3V

Vulnerability from github – Published: 2026-08-06 18:30 – Updated: 2026-08-06 18:30
VLAI
Details

URL Redirection to Untrusted Site ('Open Redirect') vulnerability in the HTML5 scrubber in rrrene html_sanitize_ex allows a remote attacker to force visitors of a page to navigate to a site of the attacker's choosing via a element in sanitized HTML. HtmlSanitizeEx.html5/1 keeps attacker-supplied elements in its output. A meta element acts on the whole document rather than on the fragment it was embedded in, so it can also declare document-wide directives such as Content-Security-Policy.

This is not cross-site scripting. Browsers do not navigate a meta refresh to a javascript: URL, so the uppercase JAVASCRIPT: filter bypass yields no script execution and none was demonstrated.

This issue affects html_sanitize_ex: from 0.3.1 before 1.5.3.

Severity
2.3 (Low)
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N
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{
  "affected": [],
  "aliases": [
    "CVE-2026-66829"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-601"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-06T16:16:49Z",
    "severity": "LOW"
  },
  "details": "URL Redirection to Untrusted Site (\u0027Open Redirect\u0027) vulnerability in the HTML5 scrubber in rrrene html_sanitize_ex allows a remote attacker to force visitors of a page to navigate to a site of the attacker\u0027s choosing via a \u003cmeta http-equiv=\"refresh\"\u003e element in sanitized HTML. HtmlSanitizeEx.html5/1 keeps attacker-supplied \u003cmeta\u003e elements in its output. A meta element acts on the whole document rather than on the fragment it was embedded in, so it can also declare document-wide directives such as Content-Security-Policy.\n\nThis is not cross-site scripting. Browsers do not navigate a meta refresh to a javascript: URL, so the uppercase JAVASCRIPT: filter bypass yields no script execution and none was demonstrated.\n\nThis issue affects html_sanitize_ex: from 0.3.1 before 1.5.3.",
  "id": "GHSA-c486-5fvq-fp3v",
  "modified": "2026-08-06T18:30:50Z",
  "published": "2026-08-06T18:30:49Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/rrrene/html_sanitize_ex/security/advisories/GHSA-2c6f-3j54-xpcr"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-66829"
    },
    {
      "type": "WEB",
      "url": "https://github.com/rrrene/html_sanitize_ex/commit/9f7e38be51edc38f132dfe994f37af5cf5e0e76f"
    },
    {
      "type": "WEB",
      "url": "https://cna.erlef.org/cves/CVE-2026-66829.html"
    },
    {
      "type": "WEB",
      "url": "https://osv.dev/vulnerability/EEF-CVE-2026-66829"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
      "type": "CVSS_V4"
    }
  ]
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
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  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


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