Vulnerability Description
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` can accumulate unbounded data when a multipart part’s header block never terminates with the required blank line (`CRLFCRLF`). The parser keeps appending incoming bytes to memory without a size cap, allowing a remote attacker to exhaust memory and cause a denial of service (DoS). Attackers can send incomplete multipart headers to trigger high memory use, leading to process termination (OOM) or severe slowdown. The effect scales with request size limits and concurrency. All applications handling multipart uploads may be affected. Versions 2.2.19, 3.1.17, and 3.2.2 cap per-part header size (e.g., 64 KiB). As a workaround, restrict maximum request sizes at the proxy or web server layer (e.g., Nginx `client_max_body_size`).
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Rack | Rack | < 2.2.19 |
Related Weaknesses (CWE)
References
- https://github.com/rack/rack/commit/589127f4ac8b5cf11cf88fb0cd116ffed4d2181ePatch
- https://github.com/rack/rack/commit/d869fed663b113b95a74ad53e1b5cae6ab31f29ePatch
- https://github.com/rack/rack/commit/e08f78c656c9394d6737c022bde087e0f33336fdPatch
- https://github.com/rack/rack/security/advisories/GHSA-wpv5-97wm-hp9cMitigationVendor Advisory
FAQ
What is CVE-2025-61772?
CVE-2025-61772 is a vulnerability with a CVSS score of 7.5 (HIGH). 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` can accumulate unbounded data when a multipart part’s header block never terminat...
How severe is CVE-2025-61772?
CVE-2025-61772 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-2025-61772?
Check the references section above for vendor advisories and patch information. Affected products include: Rack Rack.