CVE-2025-68480 in marshmallow
Summary
by MITRE • 12/23/2025
Marshmallow is a lightweight library for converting complex objects to and from simple Python datatypes. In versions from 3.0.0rc1 to before 3.26.2 and from 4.0.0 to before 4.1.2, Schema.load(data, many=True) is vulnerable to denial of service attacks. A moderately sized request can consume a disproportionate amount of CPU time. This issue has been patched in version 3.26.2 and 4.1.2.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 12/23/2025
The vulnerability identified as CVE-2025-68480 affects the Marshmallow library, a popular Python tool for serializing and deserializing complex data structures. This issue manifests in versions ranging from 3.0.0rc1 through 3.26.1 and from 4.0.0 through 4.1.1, creating a significant security concern for applications that rely on this library for data processing. The flaw specifically targets the Schema.load() method when invoked with the many=True parameter, which is commonly used to process collections of data objects. This vulnerability represents a classic denial of service condition where legitimate requests can be exploited to consume excessive computational resources.
The technical root cause of this vulnerability lies in the inefficient processing of data structures when the many=True parameter is used in Schema.load() operations. When attackers craft malicious input data, the library's deserialization logic becomes susceptible to algorithmic complexity issues that cause exponential CPU consumption. This behavior occurs because the internal parsing and validation mechanisms do not properly handle certain data patterns that lead to recursive or iterative processing that scales poorly with input size. The vulnerability falls under CWE-400, which categorizes issues related to excessive resource consumption, specifically targeting denial of service conditions. The problem is particularly insidious because it requires minimal input to trigger significant computational overhead, making it an attractive vector for attackers seeking to disrupt service availability.
The operational impact of this vulnerability extends beyond simple resource exhaustion, as it can severely compromise application availability and performance. Systems utilizing Marshmallow for API endpoints, data import processes, or batch operations become vulnerable to attacks that can cause service degradation or complete unavailability. The vulnerability affects applications across various domains including web services, data processing pipelines, and integration platforms that depend on Marshmallow for data transformation. Attackers can exploit this weakness by submitting carefully crafted requests that, while appearing moderate in size, trigger disproportionate computational overhead. This makes the vulnerability particularly dangerous in environments where applications process untrusted data from external sources, as it can be leveraged to create sustained denial of service conditions without requiring extensive computational resources from the attacker side.
Mitigation strategies for CVE-2025-68480 primarily focus on upgrading to patched versions of the Marshmallow library, specifically versions 3.26.2 and 4.1.2. Organizations should prioritize this upgrade as a critical security measure, particularly for applications handling external data inputs or operating in high-traffic environments. Additional protective measures include implementing request rate limiting, input validation, and resource monitoring to detect anomalous processing patterns that may indicate exploitation attempts. The ATT&CK framework categorizes this vulnerability under T1499.004, which covers network denial of service attacks, highlighting the need for defensive measures that can detect and prevent excessive resource consumption patterns. Security teams should also consider implementing automated scanning tools to identify affected systems and establish monitoring protocols to detect potential exploitation attempts through unusual CPU utilization patterns. Organizations should review their application code to ensure proper error handling and resource management when processing data through Marshmallow's Schema.load() method, particularly when dealing with untrusted inputs.