CVE-2026-45072: Symfony/symfony :fileExcerpt() — Unescaped Non-PHP File Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-hmr5-2xcr-v8pp",
  "modified" : "2026-05-27T21:10:44Z",
  "published" : "2026-05-27T21:10:44Z",
  "aliases" : [ "CVE-2026-45072" ],
  "summary" : "Symfony Vulnerable to stored XSS in WebProfiler CodeExtension::fileExcerpt() — Unescaped Non-PHP File Rendering",
  "details" : "### Description\n\nSymfony's profiler, a development only debug UI, renders source-code excerpts on several pages using Twig's custom `file_excerpt` filter. This filter renders PHP files via `highlight_string()` (which escapes HTML), but renders **non-PHP files** by splitting on `\\n` and interpolating each line directly into `<code>{$line}</code>` with no escaping. \n\nAn attacker who can write arbitrary bytes into any file under the project root (including e.g. `var/log/dev.log`), achieves **stored XSS** against any developer who later opens that file in the profiler.\n\n### Resolution\n\nThe `file_excerpt` filter now properly escapes each line of non-PHP files using `htmlspecialchars()` before concatenating them.\n\nThe patch for this issue is available [here](https://github.com/symfony/symfony/commit/863aa81c61166f1aa74b7732df316f76113acbdb) for branch 6.4.\n\n### Credits\n\nSymfony would like to thank Claude Mythos Preview (via Project Glasswing) for reporting the issue and providing the fix.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:U"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "symfony/symfony"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "6.4.24"
      }, {
        "fixed" : "6.4.40"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "symfony/symfony"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "7.2.9"
      }, {
        "fixed" : "7.4.12"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "symfony/symfony"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "8.0.0"
      }, {
        "fixed" : "8.0.12"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "symfony/twig-bridge"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "6.4.24"
      }, {
        "fixed" : "6.4.40"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "symfony/web-profiler-bundle"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "7.2.9"
      }, {
        "fixed" : "7.4.12"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "symfony/web-profiler-bundle"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "8.0.0"
      }, {
        "fixed" : "8.0.12"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/symfony/symfony/security/advisories/GHSA-hmr5-2xcr-v8pp"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/symfony/symfony/commit/863aa81c61166f1aa74b7732df316f76113acbdb"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/symfony/CVE-2026-45072.yaml"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/twig-bridge/CVE-2026-45072.yaml"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/web-profiler-bundle/CVE-2026-45072.yaml"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/symfony/symfony"
  }, {
    "type" : "WEB",
    "url" : "https://symfony.com/cve-2026-45072"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-79" ],
    "severity" : "LOW",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-05-27T21:10:44Z",
    "nvd_published_at" : null
  }
}