{"id":86709,"date":"2026-03-17T12:25:36","date_gmt":"2026-03-17T12:25:36","guid":{"rendered":""},"modified":"-0001-11-30T00:00:00","modified_gmt":"-0001-11-30T06:00:00","slug":"cve-2025-54581-denial-of-service-vulnerability-in-vproxy-server-versions-2-3-3-and-below","status":"publish","type":"post","link":"https:\/\/www.ameeba.com\/blog\/cve-2025-54581-denial-of-service-vulnerability-in-vproxy-server-versions-2-3-3-and-below\/","title":{"rendered":"<strong>CVE-2025-54581: Denial of Service Vulnerability in vProxy Server Versions 2.3.3 and Below<\/strong>"},"content":{"rendered":"<p><strong>Overview<\/strong><\/p>\n<p>The vulnerability CVE-2025-54581 is a critical flaw affecting vProxy Servers version 2.3.3 and below. It allows an attacker to cause a server crash resulting in a denial-of-service (DoS) attack. This exploits the untrusted data extraction from a user-controlled HTTP Proxy-Authorization header and can potentially lead to system compromise or data leakage.<\/p>\n<p><strong>Vulnerability Summary<\/strong><\/p>\n<p>CVE ID: CVE-2025-54581<br \/>\nSeverity: High (7.5\/10)<br \/>\nAttack Vector: Network<br \/>\nPrivileges Required: None<br \/>\nUser Interaction: None<br \/>\nImpact: A successful exploit of this vulnerability could cause a denial-of-service attack, potentially compromising the system and causing data leakage.<\/p>\n<p><strong>Affected Products<\/strong><\/p><div id=\"ameeb-3888602830\" 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>vProxy  | 2.3.3 and below<\/p>\n<p><strong>How the Exploit Works<\/strong><\/p>\n<p>The exploit works by an attacker manipulating the HTTP Proxy-Authorization header. This header is user-controlled and untrusted data is extracted from it. The manipulated data is passed to Extension::try_from and eventually flows into parse_ttl_extension, where it is parsed as a TTL (Time-To-Live) value. If the attacker supplies a TTL of zero (e.g. by setting the username as &#8216;configuredUser-ttl-0&#8217;), a division by zero error occurs, leading to a server crash and a subsequent denial-of-service attack.<\/p>\n<p><strong>Conceptual Example Code<\/strong><\/p><div id=\"ameeb-2014270046\" 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>Here is a conceptual example of how this vulnerability might be exploited. This could be done through an HTTP request as shown below:<\/p>\n<pre><code class=\"\" data-line=\"\">GET \/ HTTP\/1.1\nHost: target.vproxy.com\nProxy-Authorization: Basic Y29uZmlndXJlZFVzZXItdHRsLTA=<\/code><\/pre>\n<p>The Proxy-Authorization header above is a Base64 encoded string of &#8216;configuredUser-ttl-0&#8217;. The server parses this as a TTL value of zero, leading to a division by zero crash, hence causing a denial-of-service.<br \/>\nFor mitigation, it is advised to apply the vendor patch or use WAF\/IDS as temporary mitigation. The vulnerability has been fixed in vProxy server version 2.4.0.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Overview The vulnerability CVE-2025-54581 is a critical flaw affecting vProxy Servers version 2.3.3 and below. It allows an attacker to cause a server crash resulting in a denial-of-service (DoS) attack. This exploits the untrusted data extraction from a user-controlled HTTP Proxy-Authorization header and can potentially lead to system compromise or data leakage. Vulnerability Summary CVE [&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-86709","post","type-post","status-publish","format-standard","hentry"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/posts\/86709","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=86709"}],"version-history":[{"count":0,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/posts\/86709\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/media?parent=86709"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/categories?post=86709"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/tags?post=86709"},{"taxonomy":"vendor","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/vendor?post=86709"},{"taxonomy":"product","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/product?post=86709"},{"taxonomy":"attack_vector","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/attack_vector?post=86709"},{"taxonomy":"asset_type","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/asset_type?post=86709"},{"taxonomy":"severity","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/severity?post=86709"},{"taxonomy":"exploit_status","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/exploit_status?post=86709"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}