CVE-2022-44571 in Rack Gem
Summary
by MITRE • 02/09/2023
There is a denial of service vulnerability in the Content-Disposition parsingcomponent of Rack fixed in 2.0.9.2, 2.1.4.2, 2.2.4.1, 3.0.0.1. This could allow an attacker to craft an input that can cause Content-Disposition header parsing in Rackto take an unexpected amount of time, possibly resulting in a denial ofservice attack vector. This header is used typically used in multipartparsing. Any applications that parse multipart posts using Rack (virtuallyall Rails applications) are impacted.
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Analysis
by VulDB Data Team • 07/03/2025
The vulnerability identified as CVE-2022-44571 represents a critical denial of service weakness within the Rack web application framework that serves as the foundation for Ruby on Rails applications. This flaw specifically targets the Content-Disposition header parsing component, which plays a fundamental role in handling multipart form data submissions that are ubiquitous in web applications. The vulnerability stems from inefficient parsing algorithms that can be exploited through carefully crafted input sequences, causing the parsing process to consume excessive computational resources and time. According to the Common Weakness Enumeration framework, this vulnerability maps to CWE-400 which classifies it as an Uncontrolled Resource Consumption issue, specifically focusing on improper handling of input data during parsing operations. The attack vector leverages the inherent structure of HTTP headers to create malformed Content-Disposition values that trigger exponential or quadratic time complexity during processing, making it particularly dangerous for applications that process user-supplied multipart data.
The technical implementation of this vulnerability exploits the way Rack handles Content-Disposition headers during multipart request processing, which is a core functionality used by virtually all Rails applications that accept file uploads or complex form submissions. When an attacker crafts a malicious Content-Disposition header with nested or malformed parameters, the parsing routine enters into a computationally expensive state where processing time grows disproportionately with input size. This behavior creates a classic denial of service condition where legitimate requests cannot be processed due to the excessive resource consumption by the vulnerable parsing logic. The vulnerability affects all versions of Rack prior to the patched releases 2.0.9.2, 2.1.4.2, 2.2.4.1, and 3.0.0.1, making it particularly widespread across the Rails ecosystem. The ATT&CK framework categorizes this as a Resource Exhaustion technique under the T1499.004 sub-technique, specifically targeting application-level denial of service conditions that consume processing resources rather than network bandwidth.
The operational impact of CVE-2022-44571 extends beyond simple service disruption to potentially compromise the availability of entire web applications that rely on Rack for handling user input. Since virtually all Rails applications utilize multipart parsing for file uploads, form submissions, and API interactions, this vulnerability creates a widespread attack surface that can be exploited against numerous production systems. Attackers can trigger the vulnerability with relatively simple payloads that cause the application server to consume excessive CPU cycles or memory resources, leading to service unavailability for legitimate users. The vulnerability's exploitation is particularly concerning because it requires minimal sophistication to implement and can be executed against any application that processes multipart data through Rack. Organizations running affected versions of Rack face significant risk of service interruption, potential data loss, and reputational damage if their applications are not properly patched. The computational overhead introduced by this vulnerability can cause application servers to become unresponsive or crash entirely, making it a critical security concern for any production environment.
Mitigation strategies for CVE-2022-44571 focus primarily on immediate patching of affected Rack versions to the secure releases mentioned in the advisory. Organizations should prioritize updating their Rails applications to ensure they are running patched versions of Rack that contain the fixed parsing logic. Additionally, implementing input validation and sanitization measures can provide defense-in-depth protection by filtering suspicious Content-Disposition headers before they reach the vulnerable parsing routines. Network-level protections such as rate limiting and request size restrictions can help reduce the impact of exploitation attempts, though they do not address the root cause. Security teams should monitor their application logs for unusual patterns in multipart request processing that might indicate exploitation attempts, and implement proper intrusion detection systems to identify anomalous parsing behavior. The vulnerability serves as a reminder of the critical importance of keeping web application frameworks updated and maintaining comprehensive security monitoring practices to detect and respond to such threats effectively.