Resource exhaustion in Rack
CVE-2025-59830
Rack is a modular Ruby web server interface. Prior to version 2.2.18, Rack::QueryParser enforces its params_limit only for parameters separated by &, while still splitting on both & and ;. As a result, attackers could use ; separators to bypass the parameter count limit and submit more parameters than intended. Applications or middleware that directly invoke Rack::QueryParser with its default configuration (no explicit delimiter) could be exposed to increased CPU and memory consumption. This can be abused as a limited denial-of-service vector. This issue has been patched in version 2.2.18.
Vulnerability class: DoS (Denial of Service)
EPSS: 0.005 (42.0th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
Affected products
- Rack — versions < 2.2.18
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM, Mitigation, Vendor Advisory)
- security-advisories@github.com (Patch, x_refsource_MISC)
Frequently asked questions
- What is CVE-2025-59830?
- CVE-2025-59830 is a high-severity vulnerability in Rack, classified under Uncontrolled Resource Consumption. CVSS score: 7.5/10. Published 2025-09-25.
- How severe is CVE-2025-59830?
- High severity. CVSS v3 base score is 7.5 out of 10.