CVE-2021-39241 is a medium-severity vulnerability affecting HAProxy versions 2.0 before 2.0.24, 2.2 before 2.2.16, 2.3 before 2.3.13, and 2.4 before 2.4.3. This vulnerability allows an attacker to construct an HTTP method name that includes a space followed by the name of a protected resource, potentially leading to unauthorized access.
Published on August 17, 2021, the vulnerability has a CVSS score of 5.3, classified as medium severity. The risk to organizations includes unauthorized access due to improper interpretation of HTTP requests. The vulnerability is present in various versions of HAProxy, as well as in Debian Linux and Fedora distributions.
Given the nature of the vulnerability, attackers may leverage this weakness to gain access to protected resources. Organizations using affected versions of HAProxy should take immediate action to address this vulnerability.
With no public exploit confirmed and the vulnerability not listed in the KEV catalog, organizations should still prioritize patching immediately to mitigate potential risks.
Vulnerability Details
An issue was discovered in HAProxy versions prior to the specified patches. The vulnerability is characterized by an HTTP method name that may contain a space followed by a protected resource name, leading to possible unauthorized access. The CVSS 3.1 vector string is CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N, indicating a network attack vector with low complexity.
The affected products include HAProxy, Debian Linux, and Fedora, with a publication date of August 17, 2021. The absence of a specific CWE classification highlights the need for vigilance across all systems using these affected versions.
Technical Analysis
The root cause of CVE-2021-39241 lies in the improper handling of HTTP method names by HAProxy. An attacker could exploit this vulnerability by sending crafted HTTP requests that include spaces within method names, potentially leading to unauthorized access to protected resources.
The attack vector is network-based, and the attack complexity is low, requiring no privileges or user interaction. The confidentiality impact is none, while the integrity impact is low, as unauthorized access could alter resource states but not the resources themselves. There is no availability impact from this vulnerability.
Risk & Impact Analysis
Organizations utilizing HAProxy or its derivatives like Debian and Fedora face real-world risks from this vulnerability. The potential for unauthorized access poses significant threats, particularly in environments where sensitive data is processed. The low complexity of the attack increases the urgency for organizations to address this vulnerability.
Given that the CVSS score is 5.3, organizations should address this vulnerability in their priority patch cycle. It is crucial to assess the deployment of vulnerable versions and implement the necessary patches to mitigate potential risks.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
The vulnerability affects HAProxy versions 2.0 through 2.0.24, 2.2 through 2.2.16, 2.3 through 2.3.13, and 2.4 through 2.4.3. All versions prior to vendor patches are vulnerable, including Debian Linux 11.0 and Fedora versions 33 and 34.
Mitigation & Remediation
Organizations should update to the latest versions of HAProxy, specifically 2.0.24, 2.2.16, 2.3.13, and 2.4.3 or later. If patches are unavailable, consider implementing configuration hardening to limit exposure to the vulnerability.
Additionally, organizations should monitor traffic for unexpected requests and implement network controls to restrict access to sensitive endpoints.
For further guidance on security assessments, organizations can refer to resources on penetration testing and remediation strategies.
Detection Guidance
To detect potential exploitation attempts, organizations should log HTTP requests and monitor for any requests containing unusual method names or patterns indicative of this vulnerability.
Behavioral anomalies such as repeated access attempts to protected resources should also be noted. Network signatures may help identify such attack patterns.
AppSecure Threat Intelligence Insight
The long-term significance of CVE-2021-39241 highlights the importance of proper request handling in web applications. This vulnerability exemplifies how subtle issues in input handling can lead to severe security risks.
Security teams should take this as a lesson in the necessity of robust validation mechanisms to prevent similar vulnerabilities. Continuous assessment and proactive remediation strategies should be integral to security practices.
For additional insights on vulnerability management and effective security practices, organizations can refer to our vulnerability management program and the latest trends in security testing.
Understanding how vulnerabilities like CVE-2021-39241 emerge can help organizations refine their security posture and better prepare against future threats.
To enhance security measures, organizations should also consider implementing penetration testing methodologies as part of their ongoing security assessments.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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