GHSA-V3WM-QF9P-C549

Vulnerability from github – Published: 2026-06-15 17:32 – Updated: 2026-06-15 17:32
VLAI
Summary
Symfony: HtmlSanitizer URL Parser Deny Gates Underinclusive: Percent-Encoded BiDi Marks and Unicode Whitespace Bypass Visual-Spoofing Defense
Details

Description

Symfony\Component\HtmlSanitizer\TextSanitizer\UrlSanitizer::parse() rejects URLs containing raw Unicode explicit-direction BiDi formatting characters (U+202A–U+202E, U+2066–U+2069) as a defense against visual-spoofing of the rendered href. The check covers only the raw UTF-8 forms of those code points: the percent-encoded forms (%E2%80%AE for U+202E, %E2%81%A6 for U+2066, etc.) are not matched by the deny regex, survive league/uri's parse/build cycle, and are re-emitted unchanged in the sanitized URL. Any downstream consumer that decodes the link before display — phishing-detection filters that compare urldecode($href) against a domain allow-list, audit-log dashboards that show a decoded form for readability, hover-tooltip previews, federated/syndicated content where the decoder lives on the consuming side — restores the BiDi character and the visual spoof that the original defense was filed to prevent.

The same UrlSanitizer::parse() carries an ASCII-only /\s/ whitespace check (no /u modifier) intended as a backstop against malformed URLs. Without the /u modifier, PCRE's \s matches only ASCII whitespace, so Unicode whitespace characters — NBSP (U+00A0), the zero-width no-break space / BOM (U+FEFF), line/paragraph separators (U+2028, U+2029), ogham space (U+1680), the U+2000–U+200A en/em quad family, narrow / medium / ideographic spaces (U+202F, U+205F, U+3000) and NEL (U+0085) — pass through unchanged in both raw and percent-encoded forms. In hostname positions they enable lookalike spoofs (example<NBSP>.com); in path/query/fragment they enable allow-list drift when a downstream consumer strips whitespace before comparison.

Resolution

UrlSanitizer::parse() now denies BiDi formatting marks together with Unicode whitespace and the zero-width no-break space, in both the raw input and the percent-decoded form of each parsed URL component (user, pass, host, path, query, fragment). ASCII space remains tolerated in path/query/fragment via the existing percent-encoding step.

The patches for this issue are available here for branch 6.4 (and forward-ported to 7.4, 8.0 and 8.1).

Credits

Symfony would like to thank Scott Arciszewski (Trail of Bits) for reporting the issue and Nicolas Grekas for providing the fix.

Show details on source website
To clipboard 

{
  "affected": [
    {
      "package": {
        "ecosystem": "Packagist",
        "name": "symfony/html-sanitizer"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "6.1.0"
            },
            {
              "fixed": "6.4.41"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Packagist",
        "name": "symfony/html-sanitizer"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "7.0.0"
            },
            {
              "fixed": "7.4.13"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Packagist",
        "name": "symfony/html-sanitizer"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "8.0.0"
            },
            {
              "fixed": "8.0.13"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Packagist",
        "name": "symfony/symfony"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "6.1.0"
            },
            {
              "fixed": "6.4.41"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Packagist",
        "name": "symfony/symfony"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "7.0.0"
            },
            {
              "fixed": "7.4.13"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Packagist",
        "name": "symfony/symfony"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "8.0.0"
            },
            {
              "fixed": "8.0.13"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-48760"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-1007",
      "CWE-451"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-06-15T17:32:59Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "### Description\n\n`Symfony\\Component\\HtmlSanitizer\\TextSanitizer\\UrlSanitizer::parse()` rejects URLs containing raw Unicode explicit-direction BiDi formatting characters (U+202A\u2013U+202E, U+2066\u2013U+2069) as a defense against visual-spoofing of the rendered `href`. The check covers only the raw UTF-8 forms of those code points: the percent-encoded forms (`%E2%80%AE` for U+202E, `%E2%81%A6` for U+2066, etc.) are not matched by the deny regex, survive `league/uri`\u0027s parse/build cycle, and are re-emitted unchanged in the sanitized URL. Any downstream consumer that decodes the link before display \u2014 phishing-detection filters that compare `urldecode($href)` against a domain allow-list, audit-log dashboards that show a decoded form for readability, hover-tooltip previews, federated/syndicated content where the decoder lives on the consuming side \u2014 restores the BiDi character and the visual spoof that the original defense was filed to prevent.\n\nThe same `UrlSanitizer::parse()` carries an ASCII-only `/\\s/` whitespace check (no `/u` modifier) intended as a backstop against malformed URLs. Without the `/u` modifier, PCRE\u0027s `\\s` matches only ASCII whitespace, so Unicode whitespace characters \u2014 NBSP (U+00A0), the zero-width no-break space / BOM (U+FEFF), line/paragraph separators (U+2028, U+2029), ogham space (U+1680), the U+2000\u2013U+200A en/em quad family, narrow / medium / ideographic spaces (U+202F, U+205F, U+3000) and NEL (U+0085) \u2014 pass through unchanged in both raw and percent-encoded forms. In hostname positions they enable lookalike spoofs (`example\u003cNBSP\u003e.com`); in path/query/fragment they enable allow-list drift when a downstream consumer strips whitespace before comparison.\n\n### Resolution\n\n`UrlSanitizer::parse()` now denies BiDi formatting marks together with Unicode whitespace and the zero-width no-break space, in both the raw input and the percent-decoded form of each parsed URL component (`user`, `pass`, `host`, `path`, `query`, `fragment`). ASCII space remains tolerated in path/query/fragment via the existing percent-encoding step.\n\nThe patches for this issue are available [here](https://github.com/symfony/symfony/commit/b21a626fd90f5c12d2db432c629eed3e780ba2f8) for branch 6.4 (and forward-ported to 7.4, 8.0 and 8.1).\n\n### Credits\n\nSymfony would like to thank Scott Arciszewski (Trail of Bits) for reporting the issue and Nicolas Grekas for providing the fix.",
  "id": "GHSA-v3wm-qf9p-c549",
  "modified": "2026-06-15T17:32:59Z",
  "published": "2026-06-15T17:32:59Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/symfony/symfony/security/advisories/GHSA-v3wm-qf9p-c549"
    },
    {
      "type": "WEB",
      "url": "https://github.com/symfony/symfony/commit/b21a626fd90f5c12d2db432c629eed3e780ba2f8"
    },
    {
      "type": "WEB",
      "url": "https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/html-sanitizer/CVE-2026-48760.yaml"
    },
    {
      "type": "WEB",
      "url": "https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/symfony/CVE-2026-48760.yaml"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/symfony/symfony"
    },
    {
      "type": "WEB",
      "url": "https://symfony.com/cve-2026-48760"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [],
  "summary": "Symfony: HtmlSanitizer URL Parser Deny Gates Underinclusive: Percent-Encoded BiDi Marks and Unicode Whitespace Bypass Visual-Spoofing Defense"
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





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

Author Source Type Date Other

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.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • 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.


Detection rules are retrieved from Rulezet.