PYSEC-2026-1455

Vulnerability from pysec - Published: 2026-07-07 11:45 - Updated: 2026-07-07 17:24
VLAI
Details

Impact

If using keep_typographic_whitespace=False (which is the default), the sanitizer normalizes unicode to the NFKC form at the end. Some unicode characters normalize to chevrons; this allows specially crafted HTML to escape sanitization.

Patches

The problem has been fixed in 2.4.2.

Workarounds

Set keep_typographic_whitespace=True explicitly, or normalize to NFKC yourself earlier.

Impacted products
Name purl
html-sanitizer pkg:pypi/html-sanitizer
Aliases
To clipboard 

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "html-sanitizer",
        "purl": "pkg:pypi/html-sanitizer"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.4.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.0.0",
        "1.1.0",
        "1.1.1",
        "1.1.2",
        "1.1.3",
        "1.1.4",
        "1.2.0",
        "1.2.1",
        "1.3.0",
        "1.4.0",
        "1.5.0",
        "1.6.0",
        "1.6.1",
        "1.6.2",
        "1.6.3",
        "1.6.4",
        "1.7.0",
        "1.7.1",
        "1.7.2",
        "1.7.3",
        "1.8.0",
        "1.9.0",
        "1.9.1",
        "1.9.2",
        "1.9.3",
        "2.0.0",
        "2.1.0",
        "2.2.0",
        "2.3.0",
        "2.3.1",
        "2.4.0",
        "2.4.1"
      ]
    }
  ],
  "aliases": [
    "CVE-2024-34078",
    "GHSA-wvhx-q427-fgh3"
  ],
  "details": "### Impact\n\nIf using `keep_typographic_whitespace=False` (which is the default), the sanitizer normalizes unicode to the NFKC form at the end. Some unicode characters normalize to chevrons; this allows specially crafted HTML to escape sanitization.\n\n### Patches\n\nThe problem has been fixed in 2.4.2.\n\n### Workarounds\n\nSet `keep_typographic_whitespace=True` explicitly, or normalize to NFKC yourself earlier.\n",
  "id": "PYSEC-2026-1455",
  "modified": "2026-07-07T17:24:19.856844Z",
  "published": "2026-07-07T11:45:42.091141Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/matthiask/html-sanitizer/security/advisories/GHSA-wvhx-q427-fgh3"
    },
    {
      "type": "WEB",
      "url": "https://github.com/matthiask/html-sanitizer/commit/48db42fc5143d0140c32d929c46b802f96913550"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/matthiask/html-sanitizer"
    },
    {
      "type": "PACKAGE",
      "url": "https://pypi.org/project/html-sanitizer"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/advisories/GHSA-wvhx-q427-fgh3"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-34078"
    }
  ],
  "summary": "Arbitrary HTML present after sanitization because of unicode normalization"
}



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