Web Cache Poisoning

Executive Summary:

This report addresses a critical security vulnerability known as Web Cache Poisoning within our application. Web Cache Poisoning occurs when attackers manipulate caching mechanisms to inject malicious content into web caches, potentially leading to security risks such as cross-site scripting (XSS) attacks, session fixation, or data leakage. This report aims to detail the vulnerability, its potential impact on our systems and users, and actionable recommendations for mitigation.

Description of the Vulnerability:

Web Cache Poisoning vulnerabilities arise when attackers manipulate HTTP requests or responses to trick caching mechanisms into storing and serving malicious content to unsuspecting users. Attackers can exploit this vulnerability by injecting crafted headers, parameters, or payloads into requests or responses, causing web caches to cache and subsequently serve the malicious content to multiple users. Common examples include poisoning cache headers, injecting cache-control directives, or exploiting cache key weaknesses.


The impact of Web Cache Poisoning vulnerabilities can be severe, leading to various security risks including XSS attacks, session fixation, or data leakage within our application. Attackers can exploit Web Cache Poisoning to compromise user sessions, execute malicious scripts in the context of our web pages, or leak sensitive information cached by proxy servers or CDN networks. The consequences may include compromised user accounts, loss of sensitive data, or reputational damage to our organization.


The likelihood of exploitation depends on various factors including the visibility of caching mechanisms within our application, the effectiveness of cache control measures, and the attacker's knowledge and motivation. However, given the prevalence of Web Cache Poisoning attacks in web applications and the potential impact on security controls and user trust, the risk associated with this vulnerability is significant if not properly mitigated.

Steps to Reproduce:

  1. Identify caching mechanisms within our application, such as proxy servers, CDN networks, or browser caches.
  2. Manipulate HTTP requests or responses to inject malicious content or directives that trigger caching of the manipulated content.
  3. Request the manipulated content from the targeted caching mechanism and observe if it serves the injected malicious content to subsequent users.
  4. Determine if security controls such as XSS protections are bypassed or if sensitive information is leaked due to cached malicious content.

Recommendations for Developers:

  1. Implement Cache-Control Headers: Set appropriate cache-control headers to prevent caching of sensitive or dynamic content that could be manipulated by attackers.
  2. Use Cache Key Security Measures: Implement secure cache key generation mechanisms to prevent cache poisoning attacks by ensuring that each cached resource is uniquely identified and validated.


Addressing Web Cache Poisoning vulnerabilities is critical to protecting against XSS attacks, session fixation, and data leakage within our application. By implementing cache-control headers and using secure cache key generation mechanisms, we can mitigate the risks associated with Web Cache Poisoning and enhance the overall security posture of our systems.