CVE-2024-37298 in schema
Summary
by MITRE • 07/01/2024
gorilla/schema converts structs to and from form values. Prior to version 1.4.1 Running `schema.Decoder.Decode()` on a struct that has a field of type `[]struct{...}` opens it up to malicious attacks regarding memory allocations, taking advantage of the sparse slice functionality. Any use of `schema.Decoder.Decode()` on a struct with arrays of other structs could be vulnerable to this memory exhaustion vulnerability. Version 1.4.1 contains a patch for the issue.
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Analysis
by VulDB Data Team • 11/08/2024
The vulnerability identified as CVE-2024-37298 affects the gorilla/schema library, a widely-used Go package for converting structs to and from form values. This library serves as a critical component in web applications that process user input through HTML forms, making it a potential attack surface for malicious actors seeking to exploit memory allocation behaviors. The issue specifically manifests when the schema.Decoder.Decode() function processes structs containing fields of type []struct{...}, which represents slices of anonymous structs. The vulnerability stems from the library's handling of sparse slices during the decoding process, where attackers can craft malicious input that causes excessive memory allocations. This memory exhaustion vulnerability represents a significant threat to application stability and availability, as it can be exploited to consume excessive system resources and potentially cause denial of service conditions.
The technical flaw lies in how the gorilla/schema library manages memory allocation when processing nested struct arrays. When a struct contains a field of type []struct{...}, the decoder's implementation does not properly validate or limit the number of elements that can be allocated during the decoding process. Attackers can manipulate form data to specify unusually large slice sizes, causing the library to allocate substantial amounts of memory that can quickly exhaust available resources. This behavior aligns with CWE-400, which categorizes "Uncontrolled Resource Consumption" as a critical weakness that can lead to denial of service attacks. The sparse slice functionality that enables this vulnerability allows for inefficient memory usage patterns where the library may allocate memory for elements that are never actually populated, creating a vector for memory exhaustion attacks.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as it can affect the stability and performance of applications relying on form processing. Web applications that accept user input through forms and utilize the gorilla/schema library for data binding become vulnerable to memory exhaustion attacks that can degrade system performance or cause complete application crashes. Attackers can exploit this vulnerability by submitting specially crafted form data that specifies large array sizes, causing the application to consume excessive memory resources. This vulnerability particularly affects applications in high-traffic environments where multiple concurrent requests could compound the memory exhaustion effects. The attack vector operates through standard HTTP form submissions, making it accessible to attackers with minimal technical expertise while potentially causing significant disruption to legitimate users.
The mitigation strategy for CVE-2024-37298 involves upgrading to version 1.4.1 or later of the gorilla/schema library, which contains the necessary patches to address the memory allocation vulnerability. Organizations should conduct immediate vulnerability assessments to identify applications using affected versions of the library and prioritize their remediation efforts. Security teams should also implement monitoring for unusual memory consumption patterns that might indicate exploitation attempts, as well as consider implementing input validation and size limits for form data to provide additional defense in depth. This vulnerability highlights the importance of proper resource management in web application frameworks and underscores the need for regular security updates and dependency monitoring. The fix implemented in version 1.4.1 addresses the root cause by properly validating slice sizes and implementing appropriate memory allocation limits, aligning with ATT&CK technique T1499.004 for resource exhaustion attacks and providing protection against similar vulnerabilities in the future.