GHSA-H5VQ-QFCG-4M6P

Vulnerability from github – Published: 2026-05-27 20:04 – Updated: 2026-05-27 20:04
VLAI
Summary
Symfony's HtmlSanitizer URL Attributes Pass Through BiDi Override Characters → Visual href Spoofing
Details

Description

Symfony\Component\HtmlSanitizer\TextSanitizer\UrlSanitizer::parse() (used by UrlSanitizer::sanitize() and therefore by every HtmlSanitizer config that allows links or media) accepts URLs that contain Unicode explicit-direction BiDi formatting characters: U+202A–U+202E (LRE / RLE / PDF / LRO / RLO) and U+2066–U+2069 (LRI / RLI / FSI / PDI). These characters are passed through unchanged into the href / src attributes produced by HtmlSanitizer. When the resulting HTML is rendered in a browser, the override characters reverse or alter the visual ordering of the URL text, so the displayed link can differ arbitrarily from the actual destination: a classic visual-spoofing / phishing primitive against viewers of sanitized content.

Resolution

UrlSanitizer::parse() now rejects URLs containing the explicit-direction BiDi formatting code points (U+202A–U+202E, U+2066–U+2069) before invoking the underlying URL parser. As an unrelated companion fix in the same patch, spaces inside path/query/fragment are now percent-encoded rather than rejected outright, while spaces in the scheme/authority remain rejected by the post-encoding whitespace check.

The patch for this issue is available here for branch 5.4.

Credits

Symfony would like to thank Himanshu Anand for reporting the issue and Nicolas Grekas for providing the fix.

Severity
6.9 (Medium)
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
Show details on source website
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{
  "affected": [
    {
      "package": {
        "ecosystem": "Packagist",
        "name": "symfony/html-sanitizer"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "6.1.0"
            },
            {
              "fixed": "6.4.40"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Packagist",
        "name": "symfony/html-sanitizer"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "7.0.0"
            },
            {
              "fixed": "7.4.12"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Packagist",
        "name": "symfony/html-sanitizer"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "8.0.0"
            },
            {
              "fixed": "8.0.12"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Packagist",
        "name": "symfony/symfony"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "6.1.0"
            },
            {
              "fixed": "6.4.40"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Packagist",
        "name": "symfony/symfony"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "7.0.0"
            },
            {
              "fixed": "7.4.12"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Packagist",
        "name": "symfony/symfony"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "8.0.0"
            },
            {
              "fixed": "8.0.12"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-45064"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-1007",
      "CWE-451"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-27T20:04:22Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "### Description\n\n`Symfony\\Component\\HtmlSanitizer\\TextSanitizer\\UrlSanitizer::parse()` (used by `UrlSanitizer::sanitize()` and therefore by every `HtmlSanitizer` config that allows links or media) accepts URLs that contain Unicode explicit-direction BiDi formatting characters: U+202A\u2013U+202E (LRE / RLE / PDF / LRO / RLO) and U+2066\u2013U+2069 (LRI / RLI / FSI / PDI). These characters are passed through unchanged into the `href` / `src` attributes produced by `HtmlSanitizer`. When the resulting HTML is rendered in a browser, the override characters reverse or alter the visual ordering of the URL text, so the displayed link can differ arbitrarily from the actual destination: a classic visual-spoofing / phishing primitive against viewers of sanitized content.\n\n### Resolution\n\n`UrlSanitizer::parse()` now rejects URLs containing the explicit-direction BiDi formatting code points (U+202A\u2013U+202E, U+2066\u2013U+2069) before invoking the underlying URL parser. As an unrelated companion fix in the same patch, spaces inside path/query/fragment are now percent-encoded rather than rejected outright, while spaces in the scheme/authority remain rejected by the post-encoding whitespace check.\n\nThe patch for this issue is available [here](https://github.com/symfony/symfony/commit/743a435e948b897ef2b5564ac438d4beb95d2526) for branch 5.4.\n\n### Credits\n\nSymfony would like to thank Himanshu Anand for reporting the issue and Nicolas Grekas for providing the fix.",
  "id": "GHSA-h5vq-qfcg-4m6p",
  "modified": "2026-05-27T20:04:22Z",
  "published": "2026-05-27T20:04:22Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/symfony/symfony/security/advisories/GHSA-h5vq-qfcg-4m6p"
    },
    {
      "type": "WEB",
      "url": "https://github.com/symfony/symfony/commit/743a435e948b897ef2b5564ac438d4beb95d2526"
    },
    {
      "type": "WEB",
      "url": "https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/html-sanitizer/CVE-2026-45064.yaml"
    },
    {
      "type": "WEB",
      "url": "https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/symfony/CVE-2026-45064.yaml"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/symfony/symfony"
    },
    {
      "type": "WEB",
      "url": "https://symfony.com/cve-2026-45064"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Symfony\u0027s HtmlSanitizer URL Attributes Pass Through BiDi Override Characters \u2192 Visual href Spoofing"
}



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