{"id":86434,"date":"2026-02-10T22:11:49","date_gmt":"2026-02-10T22:11:49","guid":{"rendered":""},"modified":"-0001-11-30T00:00:00","modified_gmt":"-0001-11-30T06:00:00","slug":"cve-2025-48866-denial-of-service-vulnerability-in-modsecurity","status":"publish","type":"post","link":"https:\/\/www.ameeba.com\/blog\/cve-2025-48866-denial-of-service-vulnerability-in-modsecurity\/","title":{"rendered":"<strong>CVE-2025-48866: Denial of Service Vulnerability in ModSecurity<\/strong>"},"content":{"rendered":"<p><strong>Overview<\/strong><\/p>\n<p>This report covers an important vulnerability, identified as CVE-2025-48866, that affects ModSecurity, an open-source, cross-platform web application firewall engine for Apache, IIS, and Nginx. The vulnerability can lead to a denial of service, potentially compromising systems or leading to data leaks. It is critical for organizations using ModSecurity to understand and address this vulnerability to protect their systems and data.<\/p>\n<p><strong>Vulnerability Summary<\/strong><\/p>\n<p>CVE ID: CVE-2025-48866<br \/>\nSeverity: High (7.5 CVSS v3 Score)<br \/>\nAttack Vector: Network<br \/>\nPrivileges Required: None<br \/>\nUser Interaction: None<br \/>\nImpact: Denial of Service and potential system compromise or data leakage<\/p>\n<p><strong>Affected Products<\/strong><\/p><div id=\"ameeb-243964431\" 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: 700px;\">\r\n  <h2 style=\"margin-top: 0; font-size: 20px; font-weight: 600; display: flex; align-items: center;\">\r\n    <a href=\"https:\/\/www.ameeba.com\/chat\" style=\"display: inline-flex; align-items: center; margin-right: 8px;\">\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: 40px; height: 40px;\" \/>\r\n    <\/a>\r\n    A new way to communicate\r\n  <\/h2>\r\n\r\n  <p style=\"margin-bottom: 12px;\">\r\n    Ameeba Chat is built on encrypted identity, not personal profiles.\r\n  <\/p>\r\n\r\n  <p style=\"margin-bottom: 16px;\">\r\n    Message, call, share files, and coordinate with identities kept separate.\r\n  <\/p>\r\n\r\n  <ul style=\"list-style: none; padding-left: 0; margin-bottom: 20px;\">\r\n    <li>\u2022 Encrypted identity<\/li>\r\n    <li>\u2022 Ameeba Chat authenticates access<\/li>\r\n    <li>\u2022 Aliases and categories<\/li>\r\n    <li>\u2022 End-to-end encrypted chat, calls, and files<\/li>\r\n    <li>\u2022 Secure notes for sensitive information<\/li>\r\n  <\/ul>\r\n\r\n  <p style=\"font-style: italic; font-weight: 600; margin-bottom: 24px;\">\r\n    Private communication, rethought.\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: 6px; font-weight: 500;\">Download Ameeba Chat<\/a>\r\n    <a href=\"https:\/\/www.ameeba.com\/chat\" style=\"border: 1px solid #ffffff; color: #ffffff; padding: 10px 20px; text-decoration: none; border-radius: 6px; font-weight: 500;\">Learn More<\/a>\r\n  <\/div>\r\n<\/div>\r\n<\/div>\n<p>Product | Affected Versions<\/p>\n<p>ModSecurity for Apache | < 2.9.10\nModSecurity for IIS | < 2.9.10\nModSecurity for Nginx | < 2.9.10\n\n<strong>How the Exploit Works<\/strong><\/p>\n<p>The vulnerability exists within the `sanitiseArg` alias `sanitizeArg` actions of ModSecurity. An attacker can submit a large number of arguments in an HTTP request, which ModSecurity fails to handle properly. This results in a denial of service due to resource exhaustion. The same flaw can potentially be leveraged to compromise the system or leak data.<\/p>\n<p><strong>Conceptual Example Code<\/strong><\/p>\n<p>Here&#8217;s a conceptual example of a HTTP request that exploits the vulnerability:<\/p><div id=\"ameeb-3242295339\" 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<pre><code class=\"\" data-line=\"\">POST \/vulnerable\/endpoint HTTP\/1.1\nHost: target.example.com\nContent-Type: application\/x-www-form-urlencoded\narg1=value&amp;arg2=value&amp;arg3=value&amp;arg4=value&amp;...&amp;argN=value<\/code><\/pre>\n<p>In the above example, &#8216;argN&#8217; represents an excessive number of arguments that exploit the vulnerability.<\/p>\n<p><strong>Mitigation Guidance<\/strong><\/p>\n<p>The recommended mitigation is to upgrade to ModSecurity version 2.9.10 or later, which has a fix for this specific vulnerability. If upgrading is not immediately possible, a temporary workaround is to avoid using rules that contain the `sanitiseArg` or `sanitizeArg` action. Utilizing a web application firewall (WAF) or intrusion detection system (IDS) can also provide temporary mitigation.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Overview This report covers an important vulnerability, identified as CVE-2025-48866, that affects ModSecurity, an open-source, cross-platform web application firewall engine for Apache, IIS, and Nginx. The vulnerability can lead to a denial of service, potentially compromising systems or leading to data leaks. It is critical for organizations using ModSecurity to understand and address this vulnerability [&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-86434","post","type-post","status-publish","format-standard","hentry"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/posts\/86434","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=86434"}],"version-history":[{"count":0,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/posts\/86434\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/media?parent=86434"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/categories?post=86434"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/tags?post=86434"},{"taxonomy":"vendor","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/vendor?post=86434"},{"taxonomy":"product","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/product?post=86434"},{"taxonomy":"attack_vector","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/attack_vector?post=86434"},{"taxonomy":"asset_type","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/asset_type?post=86434"},{"taxonomy":"severity","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/severity?post=86434"},{"taxonomy":"exploit_status","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/exploit_status?post=86434"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}