CVE-2025-59830

Publication date 26 September 2025

Last updated 15 January 2026

Ubuntu priority

Cvss 3 Severity Score

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.

Read the notes from the security team

Status

Show unmaintained releases

Package	Ubuntu Release	Status
ruby-rack	25.10 questing	Not affected
	25.04 plucky	Fixed 2.2.7-1.1ubuntu0.25.04.3
	24.04 LTS noble	Fixed 2.2.7-1ubuntu0.4
	22.04 LTS jammy	Fixed 2.1.4-5ubuntu1.2
	20.04 LTS focal	Fixed 2.0.7-2ubuntu0.1+esm8
	18.04 LTS bionic	Ignored changes too intrusive
	16.04 LTS xenial	Ignored changes too intrusive
	14.04 LTS trusty	Ignored changes too intrusive

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Notes

mdeslaur

in 3.x, rack no longer splits on ; since the following commit: https://github.com/rack/rack/commit/ef1fc0c44e6a4b77c8fcf9b4f3bfa09f04ae8482

Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package	Patch details
ruby-rack	Upstream: 54e4ffd

Severity score breakdown

Parameter	Value
Base score	7.5 · High
Attack vector	Network
Attack complexity	Low
Privileges required	None
User interaction	None
Scope	Unchanged
Confidentiality	None
Integrity impact	None
Availability impact	High
Vector	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H