Vulnerability Description
Rack is a modular Ruby web server interface. Prior to versions 2.2.20, 3.1.18, and 3.2.3, `Rack::Request#POST` reads the entire request body into memory for `Content-Type: application/x-www-form-urlencoded`, calling `rack.input.read(nil)` without enforcing a length or cap. Large request bodies can therefore be buffered completely into process memory before parsing, leading to denial of service (DoS) through memory exhaustion. Users should upgrade to Rack version 2.2.20, 3.1.18, or 3.2.3, anu of which enforces form parameter limits using `query_parser.bytesize_limit`, preventing unbounded reads of `application/x-www-form-urlencoded` bodies. Additionally, enforce strict maximum body size at the proxy or web server layer (e.g., Nginx `client_max_body_size`, Apache `LimitRequestBody`).
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Rack | Rack | < 2.2.20 |
Related Weaknesses (CWE)
References
- https://github.com/rack/rack/commit/4e2c903991a790ee211a3021808ff4fd6fe82881Patch
- https://github.com/rack/rack/commit/cbd541e8a3d0c5830a3c9a30d3718ce2e124f9dbPatch
- https://github.com/rack/rack/commit/e179614c4a653283286f5f046428cbb85f21146fPatch
- https://github.com/rack/rack/security/advisories/GHSA-6xw4-3v39-52mmMitigationThird Party Advisory
FAQ
What is CVE-2025-61919?
CVE-2025-61919 is a vulnerability with a CVSS score of 7.5 (HIGH). Rack is a modular Ruby web server interface. Prior to versions 2.2.20, 3.1.18, and 3.2.3, `Rack::Request#POST` reads the entire request body into memory for `Content-Type: application/x-www-form-urlen...
How severe is CVE-2025-61919?
CVE-2025-61919 has been rated HIGH with a CVSS base score of 7.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2025-61919?
Check the references section above for vendor advisories and patch information. Affected products include: Rack Rack.