CVE-2025-61919
Description
A memory-exhaustion vulnerability exists in Rack when parsing application/x-www-form-urlencoded request bodies. Rack::Request#POST reads the entire request body into memory without enforcing a maximum length or cap. Attackers can exploit this by sending large form submissions, potentially causing denial of service (DoS) through memory exhaustion. Even with configured parsing limits, the issue occurs before those limits are enforced, allowing unbounded memory allocation proportional to request size.
Statement
Affectedness:
Rack 1.x, including 1.6.x, is not affected by this vulnerability. The issue exists only in Rack 2.x and 3.x, where request parsing was refactored into the QueryParser component. Since Rack 1.x does not include this component, it does not contain the vulnerable logic.
Ruby 2.x and 3.x versions shipped with Red Hat Enterprise Linux, Red Hat Openshift Core OS (RHOCS) and Red Hat In-Vehicle OS (RHIVOS) are not affected, as they do not bundle the rack RubyGem by default. Rack is a third-party gem that must be installed separately.
Mitigation
No mitigation is currently available that meets Red Hat Product Security's standards for usability, deployment, applicability, or stability beyond these configuration-based workarounds.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.5 | N/A | 7.5 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | None |
| Integrity Impact | None | N/A | None |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Crash, Exit, or Restart; DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory); DoS: Resource Consumption (Other)
If an attacker can trigger the allocation of the limited resources, but the number or size of the resources is not controlled, then the most common result is denial of service. This would prevent valid users from accessing the product, and it could potentially have an impact on the surrounding environment, i.e., the product may slow down, crash due to unhandled errors, or lock out legitimate users. For example, a memory exhaustion attack against an application could slow down the application as well as its host operating system.
Access Control,Other
Technical Impact: Bypass Protection Mechanism; Other
In some cases it may be possible to force the product to "fail open" in the event of resource exhaustion. The state of the product -- and possibly the security functionality - may then be compromised.
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