{
  "canonical_id": "symfony--CVE-2021-41270",
  "system_id": "symfony",
  "display_name": "Symfony",
  "category": "frameworks",
  "advisory_mode": "core",
  "title": "CSV Injection in symfony/serializer",
  "summary": "Description\n-----------\n\nCSV Injection, also known as Formula Injection, occurs when websites embed untrusted input inside CSV files. When a spreadsheet program opens a CSV, any cell starting with `=` is interpreted by the software as a formula and could be abused by an attacker.\n\nIn Symfony 4.1, we've added the opt-in `csv_escape_formulas` option in `CsvEncoder`, to prefix all cells starting by  `=`, `+`, `-` or `@` by a tab `\\t`. \n\nSince then, OWASP added 2 chars in that list: \n- Tab (0x09)\n- Carriage return (0x0D)\n\nThis makes our previous prefix char (Tab `\\t`) part of the vulnerable characters, and [OWASP suggests](https://owasp.org/www-community/attacks/CSV_Injection) using the single quote `'` for prefixing the value.\n\nResolution\n----------\n\nSymfony now follows the OWASP recommendations and use the single quote `'` to prefix formulas and adds the prefix to cells starting by `\\t`, `\\r` as well as `=`, `+`, `-` and `@`.\n\nThe patch for this issue is available [here](https://github.com/symfony/symfony/commit/3da6f2d45e7536ccb2a26f52fbaf340917e208a8) for branch 4.4.\n\nCredits\n-------\n\nWe would like to thank Jake Barwell for reporting the issue and J\u00e9r\u00e9my Deruss\u00e9 for fixing the issue.\n",
  "published_at": "2021-11-24T21:01:23Z",
  "updated_at": "2026-03-13T21:59:52.395727Z",
  "severity": "low",
  "cvss_score": 3.1,
  "exploit_status": "unknown",
  "source_confidence": "official",
  "official_source_url": "https://github.com/symfony/symfony/security/advisories/GHSA-2xhg-w2g5-w95x",
  "secondary_source_urls": [
    "https://nvd.nist.gov/vuln/detail/CVE-2021-41270",
    "https://github.com/symfony/symfony/pull/44243",
    "https://github.com/symfony/symfony/commit/3da6f2d45e7536ccb2a26f52fbaf340917e208a8",
    "https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/serializer/CVE-2021-41270.yaml",
    "https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/symfony/CVE-2021-41270.yaml",
    "https://github.com/symfony/symfony",
    "https://github.com/symfony/symfony/releases/tag/v5.3.12",
    "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3BPT4SF6SIXFMZARDWED5T32J7JEH3EP",
    "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QSREFD2TJT5LWKM6S4MD3W26NQQ5WJUP",
    "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/3BPT4SF6SIXFMZARDWED5T32J7JEH3EP",
    "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/QSREFD2TJT5LWKM6S4MD3W26NQQ5WJUP",
    "https://symfony.com/cve-2021-41270"
  ],
  "aliases": [
    "BIT-symfony-2021-41270",
    "CVE-2021-41270",
    "GHSA-2xhg-w2g5-w95x"
  ],
  "cve_ids": [
    "CVE-2021-41270"
  ],
  "ghsa_ids": [
    "GHSA-2xhg-w2g5-w95x"
  ],
  "osv_ids": [
    "GHSA-2xhg-w2g5-w95x"
  ],
  "affected_versions": [
    "v5.0.0",
    "v5.0.1",
    "v5.0.10",
    "v5.0.11",
    "v5.0.2",
    "v5.0.3",
    "v5.0.4",
    "v5.0.5",
    "v5.0.6",
    "v5.0.7",
    "v5.0.8",
    "v5.0.9",
    "v5.1.0",
    "v5.1.0-BETA1",
    "v5.1.0-RC1",
    "v5.1.0-RC2",
    "v5.1.1",
    "v5.1.10",
    "v5.1.11",
    "v5.1.2",
    "v4.1.0",
    "v4.1.1",
    "v4.1.10",
    "v4.1.11",
    "v4.1.12",
    "v4.1.2",
    "v4.1.3",
    "v4.1.4",
    "v4.1.5",
    "v4.1.6",
    "v4.1.7",
    "v4.1.8",
    "v4.1.9",
    "v4.2.0",
    "v4.2.0-BETA1",
    "v4.2.0-BETA2",
    "v4.2.0-RC1",
    "v4.2.1",
    "v4.2.10",
    "v4.2.11",
    "v4.1.13",
    "introduced=5.0.0, fixed<5.3.12",
    "introduced=4.1.0, fixed<4.4.35"
  ],
  "fixed_versions": [
    "5.3.12",
    "4.4.35"
  ],
  "package_name": "symfony/symfony",
  "render_markdown": true,
  "case_path": "07-framework-security/frameworks/symfony/cases/symfony-cve-2021-41270.md",
  "secure_code_topics": [
    "xss-output-encoding",
    "authz-server-side-recheck",
    "path-traversal-guard"
  ],
  "status": "generated",
  "triage_reasons": [],
  "verification_status": "triage-manual",
  "verification_mode": "synthetic",
  "last_verified_at": null,
  "last_run_id": null,
  "evidence_bundle": null,
  "historical_status": null,
  "latest_status": null,
  "browser_evidence": {
    "required": false,
    "present": false,
    "refs": []
  },
  "repro_profile_id": "xss-generic",
  "artifact_mode": "synthetic",
  "blocked_reason": null,
  "metadata": {
    "source_names": [
      "OSV Symfony"
    ],
    "source_kinds": [
      "osv-batch"
    ],
    "candidate_count": 1
  }
}