GHSA-wgmf-q9vr-vww6
MEDIUMPhpSpreadsheet HTML writer is vulnerable to Cross-Site Scripting via style information
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
phpoffice/phpspreadsheet🐘phpoffice/phpspreadsheet🐘phpoffice/phpexcelReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.
Description
Summary
\PhpOffice\PhpSpreadsheet\Writer\Html doesn't sanitize spreadsheet styling information such as font names, allowing an attacker to inject arbitrary JavaScript on the page.
PoC
Example target script:
<?php
require 'vendor/autoload.php';
$reader = \PhpOffice\PhpSpreadsheet\IOFactory::createReader("Xlsx");
$spreadsheet = $reader->load(__DIR__ . '/book.xlsx');
$writer = new \PhpOffice\PhpSpreadsheet\Writer\Html($spreadsheet);
print($writer->generateHTMLAll());
Save this file in the same directory: book.xlsx
Open index.php in a web browser. An alert should be displayed.
Impact
Full takeover of the session of users viewing spreadsheet files as HTML.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | phpoffice/phpspreadsheet | ≥ 2.0.0&&< 2.1.0 | 2.1.0 |
| 🐘Packagist | phpoffice/phpspreadsheet | all versions | 1.29.1 |
| 🐘Packagist | phpoffice/phpexcel | all versions | No fix |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for phpoffice/phpspreadsheet. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update phpoffice/phpspreadsheet to 2.1.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-wgmf-q9vr-vww6 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-wgmf-q9vr-vww6 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-wgmf-q9vr-vww6. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-wgmf-q9vr-vww6 in your dependencies?
O3 detects GHSA-wgmf-q9vr-vww6 across Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.