HTTP Request Smuggling in Eclipse Grizzly

Executive Summary

CVE-2026-12606 is a vulnerability in the Eclipse Grizzly component, which is part of the Eclipse GlassFish project. The issue is related to HTTP request smuggling.

Specifically, versions of Eclipse Grizzly before 5.0.2 cannot properly parse the trailer section in malformed trailer headers. This flaw allows attackers to inject malicious HTTP requests, potentially leading to request smuggling attacks.

• Affected versions include 4.0.0 to 4.0.2 and 5.0.0 up to but not including 5.0.2.

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Detection Guidance

Detecting this vulnerability involves checking for the presence of vulnerable versions of Eclipse Grizzly in your environment. Since the issue is related to HTTP request smuggling, you can also look for signs of malformed trailer headers in HTTP requests.

• Identify the version of Eclipse Grizzly or Eclipse GlassFish in use. Vulnerable versions are 4.0.0 to 4.0.2 and 5.0.0 up to but not including 5.0.2.
• Check logs for unusual HTTP request patterns, such as malformed trailer headers or unexpected request smuggling attempts.
• Use network scanning tools to detect HTTP request smuggling vulnerabilities. Tools like Burp Suite, OWASP ZAP, or custom scripts can be used to send malformed trailer headers and observe the server's response.
• Example command to check the version of Eclipse Grizzly (if accessible via command line or logs): grep -r "Grizzly" /path/to/glassfish/logs/ or check the version in the GlassFish admin console.

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Impact Analysis

This vulnerability can impact you in several ways if you are using an affected version of Eclipse Grizzly or Eclipse GlassFish.

• Attackers could exploit this flaw to perform HTTP request smuggling, which may allow them to bypass security controls, access sensitive data, or manipulate web traffic.
• It could lead to unauthorized actions being performed on behalf of legitimate users, such as session hijacking or privilege escalation.
• If your application relies on Eclipse Grizzly for handling HTTP requests, this vulnerability could disrupt normal operations or expose your system to further attacks.

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Compliance Impact

This vulnerability could affect compliance with common standards and regulations depending on how your system is used and what data it processes.

• GDPR: If the vulnerability leads to unauthorized access or exposure of personal data, it could result in a violation of GDPR requirements for data protection and privacy. Organizations may face fines or legal consequences if they fail to mitigate the risk.
• HIPAA: For systems handling protected health information (PHI), this vulnerability could lead to unauthorized access or disclosure of sensitive patient data, violating HIPAA's security and privacy rules.
• Other standards like PCI DSS (for payment processing) or ISO 27001 (for information security management) may also be impacted if the vulnerability exposes sensitive data or compromises system integrity.

To maintain compliance, it is important to apply patches or updates to mitigate the vulnerability and ensure that security controls are in place to protect sensitive data.

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Mitigation Strategies

To mitigate this vulnerability, follow these immediate steps:

• Upgrade Eclipse Grizzly to version 5.0.2 or later, as this version contains the fix for the improper parsing of trailer headers.
• If upgrading is not immediately possible, apply temporary mitigations such as filtering or blocking malformed HTTP requests with unusual trailer headers at the network or application firewall level.
• Monitor network traffic for signs of HTTP request smuggling attempts and block suspicious requests.
• Review and update your HTTP request handling logic to ensure proper parsing of trailer headers, if custom modifications have been made to Grizzly or GlassFish.

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