Rack is a modular Ruby web server interface. In versions prior to 2.2.19, 3.1.17, and 3.2.2, ``Rack::Multipart::Parser` stores non-file form fields (parts without a `filename`) entirely in memory as Ruby `String` objects. A single large text field in a multipart/form-data request (hundreds of megabytes or more) can consume equivalent process memory, potentially leading to out-of-memory (OOM) conditions and denial of service (DoS). Attackers can send large non-file fields to trigger excessive memory usage. Impact scales with request size and concurrency, potentially leading to worker crashes or severe garbage-collection overhead. All Rack applications processing multipart form submissions are affected. Versions 2.2.19, 3.1.17, and 3.2.2 enforce a reasonable size cap for non-file fields (e.g., 2 MiB). Workarounds include restricting maximum request body size at the web-server or proxy layer (e.g., Nginx `client_max_body_size`) and validating and rejecting unusually large form fields at the application level.
This issue has been addressed in the following products: Red Hat Enterprise Linux 10 Via RHSA-2025:19513 https://access.redhat.com/errata/RHSA-2025:19513
This issue has been addressed in the following products: Red Hat Enterprise Linux 9 Via RHSA-2025:19512 https://access.redhat.com/errata/RHSA-2025:19512
This issue has been addressed in the following products: Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions Red Hat Enterprise Linux 8.8 Telecommunications Update Service Via RHSA-2025:19647 https://access.redhat.com/errata/RHSA-2025:19647
This issue has been addressed in the following products: Red Hat Enterprise Linux 8 Via RHSA-2025:19719 https://access.redhat.com/errata/RHSA-2025:19719
This issue has been addressed in the following products: Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support Red Hat Enterprise Linux 8.6 Update Services for SAP Solutions Red Hat Enterprise Linux 8.6 Telecommunications Update Service Via RHSA-2025:19734 https://access.redhat.com/errata/RHSA-2025:19734
This issue has been addressed in the following products: Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions Via RHSA-2025:19800 https://access.redhat.com/errata/RHSA-2025:19800
This issue has been addressed in the following products: Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On Via RHSA-2025:19948 https://access.redhat.com/errata/RHSA-2025:19948
This issue has been addressed in the following products: Red Hat Enterprise Linux 9 Via RHSA-2025:20962 https://access.redhat.com/errata/RHSA-2025:20962
This issue has been addressed in the following products: Red Hat Enterprise Linux 10 Via RHSA-2025:21036 https://access.redhat.com/errata/RHSA-2025:21036
This issue has been addressed in the following products: Red Hat Enterprise Linux 7 Extended Lifecycle Support Via RHSA-2025:21696 https://access.redhat.com/errata/RHSA-2025:21696