CVE-2025-67735 is a medium-severity vulnerability affecting Netty, an asynchronous, event-driven network application framework. The issue lies in the `io.netty.handler.codec.http.HttpRequestEncoder`, which is susceptible to CRLF injection with the request URI when constructing requests. This vulnerability allows an attacker to exploit improperly sanitized URIs, leading to request smuggling. This flaw affects all applications and frameworks utilizing `HttpRequestEncoder` versions prior to 4.1.129.Final and 4.2.8.Final.
The CVSS score for this vulnerability is 6.5, categorizing it as medium severity. This rating is based on factors such as the attack vector being network-based and the low complexity of the attack. Organizations leveraging affected versions of Netty should be aware of the potential risks associated with this vulnerability, as it can facilitate unauthorized actions when exploited.
Given the nature of this vulnerability, organizations should assess their use of Netty and prioritize immediate patching to the recommended versions. The urgency lies in the capability of attackers to leverage this flaw for malicious purposes, emphasizing the need for prompt remediation.
Currently, there is no known public exploit available for CVE-2025-67735, and it is not classified as actively exploited in the wild. However, the potential for exploitation exists, and organizations are advised to remain vigilant.
Organizations should prioritize patching immediately.
Vulnerability Details
The vulnerability is detailed in the official CVE description, stating that it results from a CRLF injection in the `io.netty.handler.codec.http.HttpRequestEncoder`. This issue is classified under CWE-93, which pertains to the CRLF injection vulnerability. To mitigate this issue, it is crucial to upgrade to versions 4.1.129.Final or 4.2.8.Final, which have addressed the flaw.
Technical Analysis
The root cause of CVE-2025-67735 lies in the improper handling of the request URI within the `HttpRequestEncoder` component. Attackers may leverage this vulnerability to inject CRLF sequences into the request, leading to request smuggling. The attack vector is classified as network-based, and the complexity is rated as low, requiring no special privileges or user interaction for exploitation.
The confidentiality and integrity impacts are rated as low, indicating that the data may be exposed or altered, but no availability impact is noted. Organizations using Netty in their applications should be aware of these risks and implement proper sanitization measures to mitigate potential abuse.
Risk & Impact Analysis
Risk to organizations includes potential unauthorized access and data manipulation due to request smuggling attacks. The blast radius could be significant if the vulnerability is exploited in high-traffic environments. Given the medium CVSS score of 6.5, organizations should address this vulnerability as part of their priority patch cycle.
As this vulnerability has been publicly disclosed with a CVE ID, it is essential to assess the potential for exploitation and take proactive measures. Organizations should remain vigilant in monitoring their systems for any signs of attempts to exploit this vulnerability.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
Affected versions include all versions prior to 4.1.129.Final and 4.2.8.Final of Netty. Organizations should ensure they upgrade to the latest versions to mitigate this vulnerability.
Mitigation & Remediation
To remediate CVE-2025-67735, organizations should upgrade to Netty versions 4.1.129.Final or 4.2.8.Final. Regularly updating software components and applying security patches is essential in maintaining a secure environment. Additionally, implementing proper input sanitization for request URIs can help prevent CRLF injection vulnerabilities.
For further guidance on security testing, organizations can refer to our penetration testing services to evaluate their security posture.
Detection Guidance
Organizations should monitor logs for unusual request patterns or anomalies that could indicate attempts to exploit this vulnerability. Key indicators may include unexpected headers or malformed URIs in requests processed by Netty.
AppSecure Threat Intelligence Insight
CVE-2025-67735 highlights the importance of proper input sanitization in application frameworks. Security teams should implement rigorous testing and validation processes to catch such vulnerabilities before they can be exploited. For more information on best practices in vulnerability management, organizations can consult our article on vulnerability management programs. Additionally, our guide on penetration testing methodology can provide insights into effective security testing strategies. Lastly, organizations should review our API penetration testing guide for details on safeguarding API endpoints.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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