CVE-2025-46727

NameCVE-2025-46727
DescriptionRack is a modular Ruby web server interface. Prior to versions 2.2.14, 3.0.16, and 3.1.14, `Rack::QueryParser` parses query strings and `application/x-www-form-urlencoded` bodies into Ruby data structures without imposing any limit on the number of parameters, allowing attackers to send requests with extremely large numbers of parameters. The vulnerability arises because `Rack::QueryParser` iterates over each `&`-separated key-value pair and adds it to a Hash without enforcing an upper bound on the total number of parameters. This allows an attacker to send a single request containing hundreds of thousands (or more) of parameters, which consumes excessive memory and CPU during parsing. An attacker can trigger denial of service by sending specifically crafted HTTP requests, which can cause memory exhaustion or pin CPU resources, stalling or crashing the Rack server. This results in full service disruption until the affected worker is restarted. Versions 2.2.14, 3.0.16, and 3.1.14 fix the issue. Some other mitigations are available. One may use middleware to enforce a maximum query string size or parameter count, or employ a reverse proxy (such as Nginx) to limit request sizes and reject oversized query strings or bodies. Limiting request body sizes and query string lengths at the web server or CDN level is an effective mitigation.
SourceCVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
Debian Bugs1104927

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
ruby-rack (PTS)bullseye2.1.4-3+deb11u2vulnerable
bullseye (security)2.1.4-3+deb11u3vulnerable
bookworm2.2.6.4-1+deb12u1vulnerable
bookworm (security)2.2.13-1~deb12u1vulnerable
trixie, sid3.1.12-1vulnerable

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
ruby-racksource(unstable)(unfixed)1104927

Notes

[bullseye] - ruby-rack <postponed> (Minor issue, DoS)
https://github.com/rack/rack/security/advisories/GHSA-gjh7-p2fx-99vx
Fixed by: https://github.com/rack/rack/commit/cd6b70a1f2a1016b73dc906f924869f4902c2d74 (v3.1.14)
Fixed by: https://github.com/rack/rack/commit/2bb5263b464b65ba4b648996a579dbd180d2b712 (v3.0.16)
Fixed by: https://github.com/rack/rack/commit/3f5a4249118d09d199fe480466c8c6717e43b6e3 (v2.2.14)

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