CVE-2025-59830
Unknown Unknown - Not Provided
BaseFortify

Publication date: 2025-09-25

Last updated on: 2025-10-10

Assigner: GitHub, Inc.

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.
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Meta Information
Published
2025-09-25
Last Modified
2025-10-10
Generated
2026-06-16
AI Q&A
2025-09-25
EPSS Evaluated
2026-06-15
NVD
CVE-2025-59830
EUVD
EUVD-2025-31103
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
rack rack to 2.2.18 (exc)
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-770 The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.
CWE-400 The product does not properly control the allocation and maintenance of a limited resource.
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Executive Summary

This vulnerability exists in the Rack Ruby web server interface before version 2.2.18. The Rack::QueryParser enforces a limit on the number of parameters only for those separated by '&', but it splits parameters on both '&' and ';'. Attackers can exploit this by using ';' as a separator to bypass the parameter count limit, allowing them to submit more parameters than intended. This can lead to increased CPU and memory usage.

Impact Analysis

If your application or middleware uses Rack::QueryParser with its default configuration, this vulnerability can be exploited to cause increased CPU and memory consumption, potentially leading to a limited denial-of-service (DoS) attack.

Mitigation Strategies

Upgrade Rack to version 2.2.18 or later, where the issue has been patched to properly enforce the params_limit and prevent bypass via ';' separators.

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