CVE-2025-61919
Large request bodies can therefore be buffered completely into process memory before parsing, leading to denial of service (DoS) through memory exhaustion.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.65%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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 3.1
- 7.5 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- EPSS
- 0.65% probability · 49th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-400
- Affected
- rack/rack
- Source
- security-advisories@github.com
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-6xw4-3v39-52mmMitigation, Third Party Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.