What is Use of Web Browser Cache Containing (CWE-525)?

TL;DR: Use of Web Browser Cache Containing Sensitive Information (CWE-525) is a vulnerability where web applications fail to specify appropriate caching policies, leading to sensitive data being stored in client-side caches. Implement restrictive caching policies using headers like “no-cache” in the Cache-Control directive.

What is Use of Web Browser Cache Containing Sensitive Information?

Use of Web Browser Cache Containing Sensitive Information (CWE-525) is a type of vulnerability that occurs when web applications do not use an appropriate caching policy, leading to sensitive information being stored in client-side caches. As defined by the MITRE Corporation under CWE-525 and classified by the OWASP Foundation under A06:2025 - Insecure Design, this issue poses significant security risks.

Quick Summary

Use of Web Browser Cache Containing Sensitive Information is a critical vulnerability that can expose sensitive data such as passwords and credit card numbers. This can occur when web applications fail to specify appropriate caching policies, allowing browsers to store sensitive information in client-side caches. The risk is particularly high on public terminals like libraries and Internet cafes.

Jump to: Quick Summary · Use of Web Browser Cache Containing Sensitive Information Overview · How Use of Web Browser Cache Containing Sensitive Information Works · Business Impact of Use of Web Browser Cache Containing Sensitive Information · Use of Web Browser Cache Containing Sensitive Information Attack Scenario · How to Detect Use of Web Browser Cache Containing Sensitive Information · How to Fix Use of Web Browser Cache Containing Sensitive Information · Framework-Specific Fixes for Use of Web Browser Cache Containing Sensitive Information · How to Ask AI to Check Your Code for Use of Web Browser Cache Containing Sensitive Information · Use of Web Browser Cache Containing Sensitive Information Best Practices Checklist · Use of Web Browser Cache Containing Sensitive Information FAQ · Vulnerabilities Related to Use of Web Browser Cache Containing Sensitive Information · References · Scan Your Own Site

Use of Web Browser Cache Containing Sensitive Information Overview

What

Use of Web Browser Cache Containing Sensitive Information is a vulnerability where web applications do not specify appropriate caching policies, leading to sensitive data being stored in client-side caches.

Why it matters

This vulnerability can expose personal information such as passwords and credit card numbers on public terminals like libraries and Internet cafes, posing significant security risks.

Where it occurs

This issue commonly affects web applications that fail to implement proper cache control headers or policies for forms and web pages containing sensitive data.

Who is affected

Users accessing web applications from shared or public devices are at risk of having their sensitive information exposed through browser caches.

Who is NOT affected

Applications that do not store sensitive data in client-side caches, such as those using secure connections (HTTPS) with proper cache control headers like “no-cache” and “private,” are less likely to be vulnerable.

How Use of Web Browser Cache Containing Sensitive Information Works

Root Cause

The root cause is the lack of appropriate caching policies that prevent sensitive information from being stored in client-side caches.

Attack Flow

1. An attacker gains access to a public terminal.
2. The user’s session data or sensitive forms are cached by the browser.
3. The attacker exploits the cached data to gain unauthorized access.

Prerequisites to Exploit

• Public terminals with shared browsers.
• Lack of proper cache control headers in web applications.

Vulnerable Code

<form action="/submit" method="post">
  <input type="text" name="password" />
</form>

This code snippet shows a form that does not specify appropriate caching policies, potentially leading to sensitive data being stored in client-side caches.

Secure Code

<form action="/submit" method="post" cache-control="no-cache">
  <input type="text" name="password" />
</form>

The secure version includes the cache-control attribute set to “no-cache,” preventing sensitive data from being stored in client-side caches.

Business Impact of Use of Web Browser Cache Containing Sensitive Information

Confidentiality

Sensitive information such as passwords and credit card numbers can be exposed, leading to unauthorized access and potential financial loss.

• Financial impact: Loss due to fraud or identity theft.
• Compliance impact: Non-compliance with data protection regulations.

Use of Web Browser Cache Containing Sensitive Information Attack Scenario

1. An attacker gains access to a public terminal.
2. The user’s session data or sensitive forms are cached by the browser.
3. The attacker exploits the cached data to gain unauthorized access, leading to potential financial loss and reputational damage for the affected organization.

How to Detect Use of Web Browser Cache Containing Sensitive Information

Manual Testing

• Check web application headers for appropriate cache control directives like “no-cache” or “private.”
• Verify that sensitive forms and pages do not specify caching policies.
• Test on public terminals to observe if sensitive data is stored in client-side caches.

Automated Scanners (SAST / DAST)

Static analysis can detect missing cache control headers, while dynamic testing can simulate user sessions and verify if sensitive data is cached.

PenScan Detection

PenScan’s automated scanners actively test for this issue using tools like ZAP, Nuclei, Wapiti, Nikto, SSLyze, Dalfox, and Nmap to identify vulnerabilities in web applications.

False Positive Guidance

A finding may be a false positive if the application uses secure connections (HTTPS) with proper cache control headers that prevent sensitive data from being cached.

How to Fix Use of Web Browser Cache Containing Sensitive Information

• Implement restrictive caching policies using headers like “no-cache” in the Cache-Control directive.
• Ensure sensitive information is not stored unnecessarily in client-side caches.

Framework-Specific Fixes for Use of Web Browser Cache Containing Sensitive Information

Python/Django

from django.views.decorators.cache import never_cache

@never_cache
def my_view(request):
    # Your view logic here

The never_cache decorator ensures that the response is not cached, preventing sensitive data from being stored in client-side caches.

How to Ask AI to Check Your Code for Use of Web Browser Cache Containing Sensitive Information

Review the following Python code block for potential CWE-525 Use of Web Browser Cache Containing Sensitive Information vulnerabilities and rewrite it using restrictive caching policies:

def my_view(request):
    # Your view logic here

Use of Web Browser Cache Containing Sensitive Information Best Practices Checklist

✅ Implement restrictive caching policies using headers like “no-cache” in the Cache-Control directive. ✅ Ensure sensitive information is not stored unnecessarily in client-side caches. ✅ Test on public terminals to verify if sensitive data is cached.

Use of Web Browser Cache Containing Sensitive Information FAQ

How does the use of web browser cache containing sensitive information work?

The vulnerability occurs when a web application fails to specify an appropriate caching policy, allowing browsers to store sensitive data in client-side caches.

What are the common consequences of Use of Web Browser Cache Containing Sensitive Information?

Browsers may leave behind sensitive information such as passwords or credit card numbers for other users to exploit on public terminals like libraries and Internet cafes.

How can I protect information stored in cache?

Implement a restrictive caching policy using headers like “no-cache” in the Cache-Control directive to prevent storing sensitive data in client-side caches.

What are some potential mitigations for Use of Web Browser Cache Containing Sensitive Information?

Protect information stored in cache, use restrictive caching policies, and avoid unnecessarily storing sensitive information in the cache.

How can I detect Use of Web Browser Cache Containing Sensitive Information vulnerabilities manually?

Review web application headers to ensure they include appropriate cache control directives like “no-cache” or “private”.

What are some best practices for preventing Use of Web Browser Cache Containing Sensitive Information?

Ensure sensitive information is not cached by setting proper cache control headers and avoiding unnecessary storage of sensitive data in the cache.

How can I ask an AI assistant to check my code for Use of Web Browser Cache Containing Sensitive Information vulnerabilities?

Provide your [language] code block to an AI coding assistant and request a review for potential CWE-525 issues, suggesting fixes using restrictive caching policies.

Vulnerabilities Related to Use of Web Browser Cache Containing Sensitive Information

| CWE | Name | Relationship | |—|—|—| | CWE-524 | Use of Cache Containing Sensitive Information | ChildOf |

References

• MITRE: CWE-525
• OWASP A06 2025 - Insecure Design
• CAPEC-37
• NVD: CVE Details

Scan Your Own Site

Manual code review catches what you know to look for. An automated scan catches what you didn’t. Scan your own website using PenScan to find Use of Web Browser Cache Containing Sensitive Information and other risks before an attacker does.