GHSA-MWQM-4FW3-CJVR

Vulnerability from github – Published: 2026-06-19 19:35 – Updated: 2026-06-19 19:35
VLAI
Summary
symfony/ux-autocomplete: XSS via unescaped AJAX response data
Details

Description

The Stimulus controller shipped with symfony/ux-autocomplete renders AJAX response items into the dropdown by interpolating the text field directly into HTML template literals (<div>${item[labelField]}</div>) inside _createAutocompleteWithRemoteData(). The value is parsed as HTML rather than text, so any markup contained in the AJAX response is executed by the browser.

When the dropdown values are derived from user-supplied content, an attacker can craft a string that triggers stored XSS in the browser of any other user who later opens a page containing an autocomplete widget backed by the same data.

Resolution

The option and item renderers used in _createAutocompleteWithRemoteData() now use TomSelect's escape helper to HTML-escape the value by default. Endpoints that legitimately return HTML (for example, to highlight the search term) can opt back in to the previous behavior by setting options_as_html: true. The AutocompleteChoiceTypeExtension normalizer that previously forced options_as_html=false when autocomplete_url was set has been dropped so the opt-in is reachable from the form layer.

The patch for this issue is available here for branch 2.x (and forward-ported to 3.x).

Credits

Symfony would like to thank Alex Ashkov for reporting the issue and Hugo Alliaume for providing the fix.

Severity
5.1 (Medium)
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N
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{
  "affected": [
    {
      "package": {
        "ecosystem": "Packagist",
        "name": "symfony/ux-autocomplete"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.2.0"
            },
            {
              "fixed": "2.36.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Packagist",
        "name": "symfony/ux-autocomplete"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "3.0.0"
            },
            {
              "fixed": "3.1.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-49216"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-79"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-06-19T19:35:05Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "### Description\n\nThe Stimulus controller shipped with `symfony/ux-autocomplete` renders AJAX response items into the dropdown by interpolating the `text` field directly into HTML template literals (`\u003cdiv\u003e${item[labelField]}\u003c/div\u003e`) inside `_createAutocompleteWithRemoteData()`. The value is parsed as HTML rather than text, so any markup contained in the AJAX response is executed by the browser.\n\nWhen the dropdown values are derived from user-supplied content, an attacker can craft a string that triggers stored XSS in the browser of any other user who later opens a page containing an autocomplete widget backed by the same data.\n\n### Resolution\n\nThe `option` and `item` renderers used in `_createAutocompleteWithRemoteData()` now use TomSelect\u0027s `escape` helper to HTML-escape the value by default. Endpoints that legitimately return HTML (for example, to highlight the search term) can opt back in to the previous behavior by setting `options_as_html: true`. The `AutocompleteChoiceTypeExtension` normalizer that previously forced `options_as_html=false` when `autocomplete_url` was set has been dropped so the opt-in is reachable from the form layer.\n\nThe patch for this issue is available [here](https://github.com/symfony/ux/commit/842ae54bc74de389299f975f01aafae272cb0019) for branch 2.x (and forward-ported to 3.x).\n\n### Credits\n\nSymfony would like to thank Alex Ashkov for reporting the issue and Hugo Alliaume for providing the fix.",
  "id": "GHSA-mwqm-4fw3-cjvr",
  "modified": "2026-06-19T19:35:05Z",
  "published": "2026-06-19T19:35:05Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/symfony/ux/security/advisories/GHSA-mwqm-4fw3-cjvr"
    },
    {
      "type": "WEB",
      "url": "https://github.com/symfony/ux/commit/842ae54bc74de389299f975f01aafae272cb0019"
    },
    {
      "type": "WEB",
      "url": "https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/ux-autocomplete/CVE-2026-49216.yaml"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/symfony/ux"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "symfony/ux-autocomplete: XSS via unescaped AJAX response data"
}



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