CVE-2023-46136 is a high-severity vulnerability affecting Werkzeug, a comprehensive WSGI web application library. The vulnerability arises when an attacker uploads a file starting with CR or LF, followed by large amounts of data without these characters. The library appends this data chunk by chunk into an internal bytearray, causing a denial of service (DoS) as the CPU time required to process the multipart data can block worker processes from handling legitimate requests. This vulnerability has been patched in version 3.0.1, and organizations using affected versions must prioritize remediation.
The severity level is classified as high with a CVSS score of 8.0, indicating significant risk to organizations. The attack vector is through an adjacent network, and the complexity of the attack is low, making it accessible for potential exploitation. Given that the vulnerability allows for denial of service, organizations should prioritize patching immediately to prevent disruption to their services.
Currently, there is an exploit available on GitHub, which demonstrates the potential for this vulnerability to be weaponized. Additionally, the exploitability score sits at 2.1, underscoring the ease of exploitation. Organizations must remain vigilant and update their systems to the latest version to mitigate this risk.
Given the current threat landscape, organizations using Werkzeug should assess their version and implement the necessary updates. If patching cannot be performed immediately, consider implementing additional monitoring and network controls to detect any unusual activity indicative of exploitation attempts.
In summary, CVE-2023-46136 presents a significant risk, and organizations must take immediate action to secure their systems.
Vulnerability Details
The official description states that this vulnerability allows an attacker to cause a denial of service by sending crafted multipart data to an endpoint that will parse it. The vulnerability is identified as CWE-400 (Uncontrolled Resource Consumption), CWE-407 (Design Flaw), and CWE-787 (Out-of-bounds Write). The CVSS score is derived from various metrics, including an attack vector of adjacent network and low complexity, which means it does not require significant skill to exploit.
Technical Analysis
The root cause of this vulnerability lies in how Werkzeug processes file uploads. When an uploaded file starts with CR or LF characters, the subsequent data is appended to an internal buffer. The parsing process for multipart data does not adequately manage the size of this buffer, leading to excessive CPU usage as the size grows. This situation can effectively block the server's ability to handle legitimate requests, resulting in a denial of service.
The attack vector is adjacent network, indicating that an attacker must have access to the same network as the target application. The complexity of the attack is low, requiring no special privileges or user interaction. The impact on confidentiality, integrity, and availability is rated as high, confirming the potential severity of this vulnerability.
Risk & Impact Analysis
Risk to organizations includes significant downtime and resource consumption, potentially affecting service availability. The blast radius could extend to all applications relying on Werkzeug for their web functionalities. Given the CVSS score of 8.0, organizations should address this vulnerability in their priority patch cycle. The presence of a public exploit increases the urgency for organizations to remediate, as it could lead to widespread disruption if exploited.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | Yes |
Public PoC | Yes |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
The affected versions of Werkzeug include all versions prior to 3.0.1. Specifically, versions 2.3.0 to 2.3.7 and version 3.0.0 are vulnerable. Organizations should ensure they are using version 3.0.1 or later to mitigate risks associated with this vulnerability.
Mitigation & Remediation
Organizations should prioritize upgrading to Werkzeug version 3.0.1 or later to address this vulnerability. If immediate patching is not feasible, consider implementing network controls to limit access to the application, monitor for unusual traffic patterns, and review log files for any signs of exploitation attempts. Additionally, organizations may benefit from a thorough application security assessment to evaluate vulnerabilities within their systems. For further assistance, organizations can engage in application security assessment services.
Detection Guidance
Organizations should monitor logs for indicators of exploitation attempts, such as unusually high CPU usage or failure to handle legitimate requests. Monitoring for behavioral anomalies in the application can also serve as an indicator of potential exploitation. Network signatures that detect large multipart data submissions may also be useful in identifying potential attacks.
AppSecure Threat Intelligence Insight
The long-term significance of CVE-2023-46136 lies in its demonstration of how file upload vulnerabilities can lead to denial of service. Security teams should learn from this incident to implement robust validation of input data and to ensure proper resource management within their applications. The pattern of vulnerability exploitation in web applications emphasizes the need for continuous security assessments and proactive risk management strategies.
Organizations should consider enhancing their vulnerability management program to proactively identify and mitigate risks before they can be exploited.
Additionally, organizations should review their penetration testing methodology to ensure comprehensive coverage of potential vulnerabilities, including file uploads.
In conclusion, CVE-2023-46136 serves as a reminder of the importance of maintaining robust security practices within web applications and the need for ongoing vigilance against emerging threats.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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