Summary
Unauthorized Reflected XSS in the constructor of the Downloader class
Product: Phpspreadsheet
Version: version 3.6.0
CWE-ID: CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CVSS vector v.3.1: 8.2 (AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:H/A:N)
CVSS vector v.4.0: 8.3 (AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:H/VA:N/SC:L/SI:H/SA:L)
Description: using the /vendor/phpoffice/phpspreadsheet/samples/download.php script, an attacker can perform a XSS-type attack
Impact: execution of arbitrary JavaScript code in the browser
Vulnerable component: the constructor of the Downloader class
Exploitation conditions: an unauthorized user
Mitigation: sanitization of the name and type variables
Researcher: Aleksey Solovev (Positive Technologies)
Research
The researcher discovered zero-day vulnerability Unauthorized Reflected Cross-Site Scripting (XSS) (in the constructor of the Downloader class) in Phpspreadsheet.
The latest version (3.6.0) of the phpoffice/phpspreadsheet library was installed. The installation was carried out with the inclusion of examples.
Listing 1. Installing the phpoffice/phpspreadsheet library
$ composer require phpoffice/phpspreadsheet --prefer-source
The ./vendor/phpoffice/phpspreadsheet/samples/download.php file processes the GET parameters name and type.
Figure 1. The ./vendor/phpoffice/phpspreadsheet/samples/download.php file accepts GET parameters.
Consider the constructor of the Downloader class, where GET parameters are passed. Error is displayed without sanitization using GET parameters transmitted from the user.
Figure 2. Error is displayed without sanitization
When clicking on the following link, arbitrary JavaScript code will be executed.
Listing 2.
https://192.***.***.***/vendor/phpoffice/phpspreadsheet/samples/download.php?name=%3Cimg%20src=1%20onerror=alert()%3E&type=1
Demonstration of the execution of arbitrary JavaScript code.
Figure 3. Executing arbitrary JavaScript code
Credit
This vulnerability was discovered by Aleksey Solovev (Positive Technologies)
Impact
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-2024-56365 has a CVSS score of 7.1 (High). The vector is network-reachable, no 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 (3.7.0, 1.29.7, 2.1.6, 2.3.5); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
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. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Remediation advice
phpoffice/phpspreadsheet to 3.7.0 or later; phpoffice/phpspreadsheet to 1.29.7 or later; phpoffice/phpspreadsheet to 2.1.6 or later; phpoffice/phpspreadsheet to 2.3.5 or later
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
Frequently Asked Questions
- What is CVE-2024-56365? CVE-2024-56365 is a high-severity cross-site scripting (XSS) vulnerability in phpoffice/phpspreadsheet (composer), affecting versions >= 3.0.0, < 3.7.0. It is fixed in 3.7.0, 1.29.7, 2.1.6, 2.3.5. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
- How severe is CVE-2024-56365? CVE-2024-56365 has a CVSS score of 7.1 (High). 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.
- Which packages are affected by CVE-2024-56365?
phpoffice/phpspreadsheet(composer) (versions >= 3.0.0, < 3.7.0)phpoffice/phpexcel(composer) (versions <= 1.8.2)
- Is there a fix for CVE-2024-56365? Yes. CVE-2024-56365 is fixed in 3.7.0, 1.29.7, 2.1.6, 2.3.5. Upgrade to this version or later.
- Is CVE-2024-56365 exploitable, and should I be worried? Whether CVE-2024-56365 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
- What actually determines whether CVE-2024-56365 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.
- How do I fix CVE-2024-56365?
- Upgrade
phpoffice/phpspreadsheetto 3.7.0 or later - Upgrade
phpoffice/phpspreadsheetto 1.29.7 or later - Upgrade
phpoffice/phpspreadsheetto 2.1.6 or later - Upgrade
phpoffice/phpspreadsheetto 2.3.5 or later
- Upgrade