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@renovate renovate bot commented Sep 25, 2025

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This PR contains the following updates:

Package Change Age Confidence
rack (changelog) 2.2.17 -> 2.2.18 age confidence

GitHub Vulnerability Alerts

CVE-2025-59830

Summary

Rack::QueryParser in version < 2.2.18 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.

Details

The issue arises because Rack::QueryParser#check_query_string counts only & characters when determining the number of parameters, but the default separator regex DEFAULT_SEP = /[&;] */n splits on both & and ;. This mismatch means that queries using ; separators were not included in the parameter count, allowing params_limit to be bypassed.

Other safeguards (bytesize_limit and key_space_limit) still applied, but did not prevent this particular bypass.

Impact

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.

Rack::Request, the primary entry point for typical Rack applications, uses QueryParser in a safe way and does not appear vulnerable by default. As such, the severity is considered low, with the impact limited to edge cases where QueryParser is used directly.

Mitigation

  • Upgrade to a patched version of Rack where both & and ; are counted consistently toward params_limit.
  • If upgrading is not immediately possible, configure QueryParser with an explicit delimiter (e.g., &) to avoid the mismatch.
  • As a general precaution, enforce query string and request size limits at the web server or proxy layer (e.g., Nginx, Apache, or a CDN) to mitigate excessive parsing overhead.

Release Notes

rack/rack (rack)

v2.2.18

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This PR was generated by Mend Renovate. View the repository job log.

@renovate renovate bot requested a review from a team as a code owner September 25, 2025 20:05
@renovate renovate bot added the renovate Automated dependency updates label Sep 25, 2025
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Review the following changes in direct dependencies. Learn more about Socket for GitHub.

Diff Package Supply Chain
Security
Vulnerability Quality Maintenance License
Updatedrack@​2.2.17 ⏵ 2.2.1892100 +15100100100

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@renovate renovate bot merged commit dd436a7 into main Sep 25, 2025
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@renovate renovate bot deleted the renovate/rubygems-rack-vulnerability branch September 25, 2025 22:49
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