CVE-2025-46727 Unbounded-Parameter DoS in Rack::QueryParser
Attackers can cause denial of service by sending requests with excessive parameters, exhausting memory and CPU in Rack::QueryParser.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-46727?
CVE-2025-46727 is a high-severity denial of service vulnerability in rack, published on 7 May 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Which versions are affected by CVE-2025-46727?
6 open source packages ship an affected version, including rack. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
rack RubyGems | All versions | 2.2.14 |
rack RubyGems | All versions | 2.2.14 |
rack RubyGems | From 3.0 | 3.0.16 |
rack RubyGems | From 3.0 | 3.0.16 |
rack RubyGems | From 3.1 | 3.1.14 |
rack RubyGems | From 3.1 | 3.1.14 |
Linux distribution packages (26)
cockpit-ha-cluster Red Hat:enterprise_linux:10.0 | All versions | 0:0.12.0-3.el10_0.2 |
pcs Red Hat:enterprise_linux:10.0 | All versions | 0:0.12.0-3.el10_0.2 |
pcs-snmp Red Hat:enterprise_linux:10.0 | All versions | 0:0.12.0-3.el10_0.2 |
pcs Red Hat:enterprise_linux:7::server | All versions | 0:0.9.169-3.el7_9.4 |
pcs-debuginfo Red Hat:enterprise_linux:7::server | All versions | 0:0.9.169-3.el7_9.4 |
pcs-snmp Red Hat:enterprise_linux:7::server | All versions | 0:0.9.169-3.el7_9.4 |
pcs Red Hat:enterprise_linux:9::highavailability | All versions | 0:0.11.9-2.el9_6.1 |
pcs-snmp Red Hat:enterprise_linux:9::highavailability | All versions | 0:0.11.9-2.el9_6.1 |
pcs Red Hat:enterprise_linux:9::resilientstorage | All versions | 0:0.11.9-2.el9_6.1 |
pcs-snmp Red Hat:enterprise_linux:9::resilientstorage | All versions | 0:0.11.9-2.el9_6.1 |
pcs Red Hat:rhel_eus:9.2::highavailability | All versions | 0:0.11.4-7.el9_2.5 |
pcs-snmp Red Hat:rhel_eus:9.2::highavailability | All versions | 0:0.11.4-7.el9_2.5 |
pcs Red Hat:rhel_eus:9.2::resilientstorage | All versions | 0:0.11.4-7.el9_2.5 |
pcs-snmp Red Hat:rhel_eus:9.2::resilientstorage | All versions | 0:0.11.4-7.el9_2.5 |
pcs Red Hat:rhel_eus:9.4::highavailability | All versions | 0:0.11.7-2.el9_4.4 |
pcs-snmp Red Hat:rhel_eus:9.4::highavailability | All versions | 0:0.11.7-2.el9_4.4 |
pcs Red Hat:rhel_eus:9.4::resilientstorage | All versions | 0:0.11.7-2.el9_4.4 |
pcs-snmp Red Hat:rhel_eus:9.4::resilientstorage | All versions | 0:0.11.7-2.el9_4.4 |
rubygem-rack Red Hat:satellite:6.16::el8 | All versions | 0:2.2.14-1.el8sat |
rubygem-rack Red Hat:satellite:6.16::el9 | All versions | 0:2.2.14-1.el9sat |
rubygem-rack Red Hat:satellite:6.17::el9 | All versions | 0:2.2.14-1.el9sat |
rubygem-rack Red Hat:satellite_capsule:6.16::el8 | All versions | 0:2.2.14-1.el8sat |
rubygem-rack Red Hat:satellite_capsule:6.16::el9 | All versions | 0:2.2.14-1.el9sat |
rubygem-rack Red Hat:satellite_capsule:6.17::el9 | All versions | 0:2.2.14-1.el9sat |
pcs Rocky Linux:9 | All versions | 0:0.11.9-2.el9_6.1 |
rubygem-rack-2.2 openSUSE:Tumbleweed | All versions | 2.2.14-1.1 |
Products include Rack Rack.
How do I fix CVE-2025-46727?
Upgrade rack to a fixed version for your release line: 2.2.14, 3.0.16 or 3.1.14.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2025-46727 being exploited?
There is no known exploitation of CVE-2025-46727 in the wild and no public exploit code.
Other vulnerabilities in rack
- CVE-2026-34785 Rack: Local file inclusion in `Rack::Static` via URL Prefix Matching
- CVE-2026-34827 Rack: Algorithmic-Complexity DoS in Rack::Multipart::Parser
- CVE-2026-34829 Rack: Denial of Service via Unbounded Multipart File Upload Without Content-Length
- CVE-2026-22860 Rack has a Directory Traversal via Rack:Directory
- CVE-2025-61919 Rack is vulnerable to a memory-exhaustion DoS through unbounded URL-encoded body parsing
Sources
Also known as DEBIAN-CVE-2025-46727, GHSA-gjh7-p2fx-99vx, MINI-7rf6-4wjc-h5q8, MINI-m77v-pp9v-prv2, OESA-2025-2211, OESA-2025-2212 and 14 more.