Rack 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.
History

Tue, 17 Jun 2025 20:00:00 +0000

Type Values Removed Values Added
First Time appeared Rack
Rack rack
CPEs cpe:2.3:a:rack:rack:*:*:*:*:*:ruby:*:*
cpe:2.3:a:rack:rack:*:-:*:*:*:ruby:*:*
Vendors & Products Rack
Rack rack

Sat, 31 May 2025 00:15:00 +0000

Type Values Removed Values Added
CPEs cpe:/a:redhat:rhel_e4s:8.4::highavailability
cpe:/a:redhat:rhel_tus:8.4::highavailability
cpe:/o:redhat:enterprise_linux:10.0
cpe:/o:redhat:enterprise_linux:7

Thu, 29 May 2025 19:30:00 +0000

Type Values Removed Values Added
First Time appeared Redhat rhel E4s
Redhat rhel Eus
Redhat rhel Tus
CPEs cpe:/a:redhat:enterprise_linux:9::highavailability
cpe:/a:redhat:rhel_e4s:8.6::highavailability
cpe:/a:redhat:rhel_e4s:9.0::highavailability
cpe:/a:redhat:rhel_eus:8.8::highavailability
cpe:/a:redhat:rhel_eus:9.2::highavailability
cpe:/a:redhat:rhel_eus:9.4::highavailability
cpe:/a:redhat:rhel_tus:8.6::highavailability
Vendors & Products Redhat rhel E4s
Redhat rhel Eus
Redhat rhel Tus

Wed, 28 May 2025 17:15:00 +0000

Type Values Removed Values Added
First Time appeared Redhat enterprise Linux
CPEs cpe:/a:redhat:enterprise_linux:8::highavailability
Vendors & Products Redhat enterprise Linux

Thu, 15 May 2025 06:45:00 +0000

Type Values Removed Values Added
First Time appeared Redhat
Redhat satellite
Redhat satellite Capsule
CPEs cpe:/a:redhat:satellite:6.16::el8
cpe:/a:redhat:satellite:6.16::el9
cpe:/a:redhat:satellite:6.17::el9
cpe:/a:redhat:satellite_capsule:6.16::el8
cpe:/a:redhat:satellite_capsule:6.16::el9
cpe:/a:redhat:satellite_capsule:6.17::el9
Vendors & Products Redhat
Redhat satellite
Redhat satellite Capsule

Thu, 08 May 2025 14:30:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

threat_severity

Important


Thu, 08 May 2025 14:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Wed, 07 May 2025 23:15:00 +0000

Type Values Removed Values Added
Description Rack 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.
Title Unbounded-Parameter DoS in Rack::QueryParser
Weaknesses CWE-400
CWE-770
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published: 2025-05-07T23:07:40.563Z

Updated: 2025-05-08T14:01:06.865Z

Reserved: 2025-04-28T20:56:09.084Z

Link: CVE-2025-46727

cve-icon Vulnrichment

Updated: 2025-05-08T14:00:46.517Z

cve-icon NVD

Status : Analyzed

Published: 2025-05-07T23:15:54.267

Modified: 2025-06-17T19:44:47.010

Link: CVE-2025-46727

cve-icon Redhat

Severity : Important

Publid Date: 2025-05-07T23:07:40Z

Links: CVE-2025-46727 - Bugzilla