CVE-2025-59830
As a result, attackers could use ; separators to bypass the parameter count limit and submit more parameters than intended.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.57%). 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 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.
- 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
- 0.57% probability · 46th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-400, CWE-770
- Affected
- rack/rack
- Source
- security-advisories@github.com
References
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.