{"id":87036,"date":"2026-06-04T00:17:11","date_gmt":"2026-06-04T00:17:11","guid":{"rendered":""},"modified":"-0001-11-30T00:00:00","modified_gmt":"-0001-11-30T06:00:00","slug":"cve-2025-59830-rack-queryparser-parameter-count-limit-bypass-vulnerability-in-ruby","status":"publish","type":"post","link":"https:\/\/www.ameeba.com\/blog\/cve-2025-59830-rack-queryparser-parameter-count-limit-bypass-vulnerability-in-ruby\/","title":{"rendered":"<strong>CVE-2025-59830: Rack::QueryParser Parameter Count Limit Bypass Vulnerability in Ruby<\/strong>"},"content":{"rendered":"<p><strong>Overview<\/strong><\/p>\n<p>This report covers a significant vulnerability found in Rack, a modular Ruby web server interface. The flaw, identified as CVE-2025-59830, is a parameter count limit bypass vulnerability that may lead to increased CPU and memory consumption, potentially causing a denial of service. This vulnerability is of importance to all businesses and individuals using affected versions of Rack, as it poses a risk to system stability and data security.<\/p>\n<p><strong>Vulnerability Summary<\/strong><\/p>\n<p>CVE ID: CVE-2025-59830<br \/>\nSeverity: High (CVSS: 7.5)<br \/>\nAttack Vector: Network<br \/>\nPrivileges Required: None<br \/>\nUser Interaction: None<br \/>\nImpact: Potential system compromise or data leakage due to increased CPU and memory consumption<\/p>\n<p><strong>Affected Products<\/strong><\/p><div id=\"ameeb-3010328931\" class=\"ameeb-content-2 ameeb-entity-placement\"><div style=\"border-left: 4px solid #555; padding-left: 20px; margin: 48px 0; font-family: Roboto, sans-serif; color: #ffffff; line-height: 1.6; max-width: 720px;\">\r\n  <h2 style=\"margin-top: 0; font-size: 22px; font-weight: 600; display: flex; align-items: center; letter-spacing: -0.02em;\">\r\n    <a href=\"https:\/\/www.ameeba.com\/chat\" style=\"display: inline-flex; align-items: center; margin-right: 10px;\">\r\n      <img decoding=\"async\" src=\"https:\/\/www.ameeba.com\/blog\/wp-content\/uploads\/2025\/10\/Best-App-icon-Ameeba.png\" alt=\"Ameeba Chat Icon\" style=\"width: 42px; height: 42px;\" \/>\r\n    <\/a>\r\n    Share secrets securely\r\n  <\/h2>\r\n\r\n  <p style=\"margin-bottom: 14px; color: #d1d5db;\">\r\n    Ameeba is private infrastructure for communication and sensitive work built on encrypted identity instead of exposed corporate identity systems.\r\n  <\/p>\r\n\r\n  <p style=\"margin-bottom: 18px; color: #a1a1aa;\">\r\n    Passwords, credentials, confidential files, screenshots, internal discussions, sensitive AI context, and private coordination should not become exposed across ordinary communication platforms.\r\n  <\/p>\r\n\r\n  <ul style=\"list-style: none; padding-left: 0; margin-bottom: 24px; color: #e4e4e7;\">\r\n    <li style=\"margin-bottom: 8px;\">\u2022 Encrypted identity<\/li>\r\n    <li style=\"margin-bottom: 8px;\">\u2022 Private Spaces for organizations and teams<\/li>\r\n    <li style=\"margin-bottom: 8px;\">\u2022 End-to-end encrypted chat, calls, files, and notes<\/li>\r\n    <li style=\"margin-bottom: 8px;\">\u2022 Sensitive AI work and protected collaboration<\/li>\r\n    <li>\u2022 Built for information that cannot leak<\/li>\r\n  <\/ul>\r\n\r\n  <p style=\"font-style: italic; font-weight: 600; margin-bottom: 24px; color: #ffffff;\">\r\n    Our mission is to secure human work alongside AI.\r\n  <\/p>\r\n\r\n  <div style=\"display: flex; flex-wrap: wrap; gap: 12px;\">\r\n    <a href=\"https:\/\/www.ameeba.com\/chat\/download\" style=\"background-color: #ffffff; color: #000000; padding: 10px 20px; text-decoration: none; border-radius: 8px; font-weight: 500;\">\r\n      Download Ameeba\r\n    <\/a>\r\n\r\n    <a href=\"https:\/\/www.ameeba.com\/chat\" style=\"border: 1px solid #ffffff; color: #ffffff; padding: 10px 20px; text-decoration: none; border-radius: 8px; font-weight: 500;\">\r\n      Learn More\r\n    <\/a>\r\n  <\/div>\r\n<\/div><\/div>\n<p>Product | Affected Versions<\/p>\n<p>Rack | Prior to 2.2.18<\/p>\n<p><strong>How the Exploit Works<\/strong><\/p>\n<p>The vulnerability lies in the Rack::QueryParser module which enforces its params_limit only for parameters separated by &#038;, while it should also split on ;. This allows attackers to bypass the parameter count limit by using ; separators to submit more parameters than intended. The impact is increased CPU and memory usage, which can be leveraged for a denial-of-service attack.<\/p>\n<p><strong>Conceptual Example Code<\/strong><\/p><div id=\"ameeb-3390714521\" class=\"ameeb-content ameeb-entity-placement\"><div class=\"poptin-embedded\" data-id=\"f6b387694f681\"><\/div>\r\n\r\n\r\n\r\n\r\n\r\n<\/div>\n<p>The following is a conceptual example of how the vulnerability might be exploited. This example uses a hypothetical HTTP request with a payload that abuses the parameter count bypass vulnerability.<\/p>\n<pre><code class=\"\" data-line=\"\">POST \/vulnerable\/endpoint HTTP\/1.1\nHost: target.example.com\nContent-Type: application\/x-www-form-urlencoded\nparam1=value1&amp;param2=value2;param3=value3;param4=value4;param5=value5;...;paramN=valueN<\/code><\/pre>\n<p>In the above example, the attacker is sending a POST request with more parameters than the server is designed to handle, using the ; character to bypass the parameter count limit.<\/p>\n<p><strong>Mitigation<\/strong><\/p>\n<p>It is recommended to apply the vendor patch as soon as possible. If immediate patching is not possible, using a Web Application Firewall (WAF) or Intrusion Detection System (IDS) can serve as temporary mitigation. The vulnerability has been patched in Rack version 2.2.18.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Overview This report covers a significant vulnerability found in Rack, a modular Ruby web server interface. The flaw, identified as CVE-2025-59830, is a parameter count limit bypass vulnerability that may lead to increased CPU and memory consumption, potentially causing a denial of service. This vulnerability is of importance to all businesses and individuals using affected [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"om_disable_all_campaigns":false,"footnotes":""},"categories":[],"tags":[],"vendor":[],"product":[],"attack_vector":[],"asset_type":[],"severity":[],"exploit_status":[],"class_list":["post-87036","post","type-post","status-publish","format-standard","hentry"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/posts\/87036","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/comments?post=87036"}],"version-history":[{"count":0,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/posts\/87036\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/media?parent=87036"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/categories?post=87036"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/tags?post=87036"},{"taxonomy":"vendor","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/vendor?post=87036"},{"taxonomy":"product","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/product?post=87036"},{"taxonomy":"attack_vector","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/attack_vector?post=87036"},{"taxonomy":"asset_type","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/asset_type?post=87036"},{"taxonomy":"severity","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/severity?post=87036"},{"taxonomy":"exploit_status","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/exploit_status?post=87036"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}