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)
Published · last modified .
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.
EPSS exploit prediction
EPSS: 0.006 (45.2th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 45th percentile — 45.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.006 · newest: 0.006 · change: 0.000
Affected products
- Rack — versions < 2.2.18
Weakness classification (CWE)
References
- github.com/rack/rack/security/advisories/GHSA-625h-95r8-8xpm (Mitigation, Vendor Advisory)
- github.com/rack/rack/commit/54e4ffdd5affebcb0c015cc6ae74635c0831ed71 (Patch)
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.