Overview
CVE-2024-3884 is a high-severity vulnerability affecting Undertow, a flexible performant web server written in Java. This flaw can be exploited by unauthorized remote attackers to trigger a Denial of Service (DoS) attack. The vulnerability stems from how Undertow parses large form data encoded with the `application/x-www-form-urlencoded` content type. Specifically, the `FormEncodedDataDefinition.doParse(StreamSourceChannel)` method is susceptible to an OutOfMemory (OOM) error when processing exceedingly large form data, effectively crashing the server.
Technical Details
The vulnerability resides within the `FormEncodedDataDefinition.doParse(StreamSourceChannel)` method in Undertow. When a server using Undertow receives a request with the `application/x-www-form-urlencoded` content type, this method is invoked to parse the incoming data. An attacker can craft a malicious request with an exceptionally large form data payload. When `doParse` attempts to process this massive data, it can lead to excessive memory consumption, ultimately resulting in an `OutOfMemoryError` and causing the Undertow server to become unresponsive and effectively denying service to legitimate users. The root cause is the lack of proper size validation or resource management when handling excessively large form data.
CVSS Analysis
The Common Vulnerability Scoring System (CVSS) score for CVE-2024-3884 is 7.5, indicating a HIGH severity. This score reflects the potential impact of the vulnerability and the relative ease with which it can be exploited.
- Base Score: 7.5
- Vector String: (Example, this would vary depending on the specific details, but something like: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
- Explanation: The vulnerability is network-exploitable (AV:N) with low attack complexity (AC:L). No privileges are required (PR:N) and no user interaction is needed (UI:N). The scope is unchanged (S:U) and the impact is high availability (A:H), as the attack results in a denial of service. There is no impact to confidentiality (C:N) or integrity (I:N).
Possible Impact
The exploitation of CVE-2024-3884 can have significant consequences:
- Denial of Service (DoS): The primary impact is a denial of service, rendering the affected Undertow server unavailable to legitimate users. This can disrupt critical services and applications relying on the server.
- Service Interruption: Exploitation can lead to prolonged service outages, impacting business operations and user experience.
- Resource Exhaustion: Successful exploitation can exhaust server resources (CPU, memory), potentially affecting other applications running on the same infrastructure.
Mitigation and Patch Steps
To mitigate the risk posed by CVE-2024-3884, the following steps are recommended:
- Apply the Latest Patches: The most effective mitigation is to apply the latest security patches released by the Undertow maintainers or the distribution vendor providing Undertow. Check the official Undertow website and security advisories for available patches.
- Implement Request Size Limits: Configure Undertow to enforce strict limits on the size of incoming requests, particularly for `application/x-www-form-urlencoded` data. This can prevent attackers from sending excessively large payloads.
- Web Application Firewall (WAF): Deploy a Web Application Firewall (WAF) with rules to detect and block malicious requests targeting this vulnerability. A WAF can filter out requests with unusually large form data payloads.
- Input Validation: Implement robust input validation on the server-side to ensure that all incoming data conforms to expected formats and sizes.
- Resource Monitoring: Continuously monitor server resource utilization (CPU, memory) to detect any anomalies that might indicate an ongoing DoS attack.
References
Red Hat CVE Database: CVE-2024-3884
Red Hat Bugzilla: Issue 2275287
