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.

CVSS 3.1

7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS

0.6% chance of exploitation in the next 30 days; higher than 47% of CVEs (scores of 2026-10-25)

CWEs

CWE-400, CWE-770

Published

2025-09-25

Modified

2026-10-19

Record from

the NVD, synced 2026-10-19

Affected

• rack:rack

Packages (OSV)

References

• https://github.com/rack/rack/commit/54e4ffdd5affebcb0c015cc6ae74635c0831ed71
• https://github.com/rack/rack/security/advisories/GHSA-625h-95r8-8xpm

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