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March 4, 2025
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How to Fix CVE-2025-1867: the Critical HTTP Request Smuggling Vulnerability in libhv Library?
This article addresses a critical security vulnerability, CVE-2025-1867, affecting the libhv library. This flaw allows for HTTP Request Smuggling, potentially enabling attackers to manipulate HTTP requests and responses. This article provides a detailed explanation of the vulnerability, its potential impact, affected products, and, most importantly, guidance on how to mitigate or fix the issue. The information is tailored for security professionals, including those in DevSecOps, application security, product security, vulnerability management, penetration testing, and security operations teams, who are responsible for securing applications and infrastructure that utilize the libhv library. We aim to equip you with the knowledge and steps necessary to protect your systems from exploitation.
A Short Introduction to libhv
libhv is a lightweight cross-platform library providing event loop, non-blocking I/O, timer management, and HTTP/WebSocket client and server functionalities. It is designed for high-performance networking applications and is often embedded in various software projects requiring efficient handling of network communications. Due to its ease of use and performance benefits, libhv is utilized across diverse applications.
Summary of CVE-2025-1867
CVE ID: CVE-2025-1867
Description: Inconsistent Interpretation of HTTP Requests ('HTTP Request Smuggling')
CVSS Score: 10.0 (Critical)
CVSS Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVE-2025-1867 describes an HTTP Request Smuggling vulnerability within the ithewei libhv library. Specifically, versions up to and including 1.3.3 are susceptible. This vulnerability arises from inconsistencies in how the library interprets HTTP requests, allowing attackers to inject malicious requests into a legitimate HTTP stream. Due to the critical nature of request smuggling vulnerabilities and the potential for complete compromise, a CVSS score of 10.0 is assigned. The high score reflects the ease of exploitation (low attack complexity, no required privileges or user interaction) and the significant impact on confidentiality, integrity, and availability.
Impact of CVE-2025-1867
The successful exploitation of CVE-2025-1867 can lead to severe consequences for web applications utilizing the vulnerable libhv library. Attackers can leverage this vulnerability to bypass security controls, potentially intercept or modify HTTP traffic, and conduct sophisticated web-based attacks. This can result in the compromise of the confidentiality, integrity, and availability of affected web applications. Imagine a scenario where an attacker can inject malicious JavaScript code into a user's session, leading to data theft or account takeover. Furthermore, request smuggling can be used to poison caches, redirect users to malicious websites, or even gain unauthorized access to sensitive internal resources. The ability to manipulate HTTP requests gives attackers a powerful foothold to launch a wide range of attacks.
Products Affected by CVE-2025-1867
The following products and versions are affected by the HTTP Request Smuggling vulnerability:
|
Product
|
Version(s) Affected
|
|---|---|
|
libhv
|
<= 1.3.3
|
It is crucial to note that any application or service that utilizes the libhv library version 1.3.3 or earlier is potentially vulnerable. There are currently no explicitly listed non-affected products, therefore, it's important to check the libhv version to verify if any of your applications are affected by the vulnerability.
How to Check Your Product is Vulnerable?
To determine if your application or system is vulnerable to CVE-2025-1867, follow these steps:
Identify libhv Usage: Inventory all systems and applications within your environment and identify those that utilize the libhv library.
Check libhv Version: For each identified system, determine the version of libhv being used. This can typically be done by inspecting the application's dependencies or by querying the library itself.
Network Traffic Analysis: Monitor network traffic for unusual HTTP request patterns. Look for discrepancies in Content-Length and Transfer-Encoding headers, which are common indicators of request smuggling attempts.
Web Application Firewall (WAF) Monitoring: If you have a WAF deployed, review its logs for any alerts related to HTTP request anomalies. WAFs can often detect and block request smuggling attacks.
How to Fix CVE-2025-1867?
The primary remediation strategy for CVE-2025-1867 is to upgrade the libhv library to a version beyond 1.3.3, where the vulnerability has been addressed. You can find additional details about the vulnerability at NVD NIST.
Upgrade libhv: Upgrade to the latest version of libhv as soon as it becomes available. This is the most effective way to eliminate the vulnerability. Monitor the official libhv repository or website for announcements regarding security updates.
Implement Network-Level Filtering: Deploy network-level filtering to detect and block suspicious HTTP requests. Focus on requests with conflicting Content-Length and Transfer-Encoding headers.
Web Application Firewall (WAF) Rules: Implement or update WAF rules to specifically protect against HTTP Request Smuggling attacks. WAFs can inspect HTTP traffic and block malicious requests before they reach the application.
Temporary Isolation: If immediate patching is not possible, consider temporarily isolating affected systems to reduce the risk of exploitation.
Monitor Official Channels: Continuously monitor official libhv channels (e.g., GitHub repository, mailing lists) for any security updates or patches related to this vulnerability.
Input Validation: Ensure robust input validation is implemented throughout your application to prevent the injection of malicious data into HTTP requests.
By following these steps, you can significantly reduce the risk posed by CVE-2025-1867 and protect your applications from potential attacks.
In conclusion, addressing CVE-2025-1867 requires a proactive approach, including identifying vulnerable systems, applying necessary updates, and implementing additional security measures. By taking these steps, security professionals can effectively mitigate the risk posed by this critical vulnerability and safeguard their applications and data. For more in-depth information, consider exploring what is a vulnerability to better understand the underlying issues.
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Arun KL
Arun KL is a cybersecurity professional with 15+ years of experience in IT infrastructure, cloud security, vulnerability management, Penetration Testing, security operations, and incident response. He is adept at designing and implementing robust security solutions to safeguard systems and data. Arun holds multiple industry certifications including CCNA, CCNA Security, RHCE, CEH, and AWS Security.
