{"id":57780,"date":"2025-07-06T03:37:08","date_gmt":"2025-07-06T03:37:08","guid":{"rendered":""},"modified":"2025-08-09T23:04:16","modified_gmt":"2025-08-10T05:04:16","slug":"cve-2025-6916-critical-authentication-bypass-vulnerability-in-totolink-t6-4-1-5cu-748-b20211015","status":"publish","type":"post","link":"https:\/\/www.ameeba.com\/blog\/cve-2025-6916-critical-authentication-bypass-vulnerability-in-totolink-t6-4-1-5cu-748-b20211015\/","title":{"rendered":"<strong>CVE-2025-6916: Critical Authentication Bypass Vulnerability in TOTOLINK T6 4.1.5cu.748_B20211015<\/strong>"},"content":{"rendered":"<p><strong>Overview<\/strong><\/p>\n<p>In the world of cybersecurity, few things are as unsettling as the discovery of a critical vulnerability. And that&#8217;s exactly what we&#8217;re dealing with in the case of CVE-2025-6916, a troubling flaw in the TOTOLINK T6 4.1.5cu.748_B20211015. This <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-6426-executable-file-warning-vulnerability-in-firefox-for-macos\/\"  data-wpil-monitor-id=\"64298\">vulnerability affects a crucial function of the Form_Login file<\/a>, specifically the manipulation of the authCode\/goURL argument, leading to missing authentication. Given the <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-32281-high-severity-missing-authorization-vulnerability-in-focuxtheme-wpkit-for-elementor\/\"  data-wpil-monitor-id=\"65303\">severity of the vulnerability<\/a>, its implications are far-reaching, potentially affecting all users of this version of TOTOLINK T6. This is a matter of high concern as it opens up <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-6435-firefox-vulnerability-leading-to-potential-system-compromise-and-data-leakage\/\"  data-wpil-monitor-id=\"64818\">potential avenues for system compromise or data<\/a> leakage.<\/p>\n<p><strong>Vulnerability Summary<\/strong><\/p>\n<p>CVE ID: CVE-2025-6916<br \/>\nSeverity: Critical (8.8 CVSS Severity Score)<br \/>\nAttack Vector: Network<br \/>\nPrivileges Required: None<br \/>\nUser Interaction: None<br \/>\nImpact: <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-52717-sql-injection-vulnerability-in-lifterlms-leads-to-potential-system-compromise\/\"  data-wpil-monitor-id=\"65425\">Potential system<\/a> compromise or data leakage<\/p>\n<p><strong>Affected Products<\/strong><\/p><div id=\"ameeb-3285430727\" 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>TOTOLINK T6 | 4.1.5cu.748_B20211015<\/p>\n<p><strong>How the Exploit Works<\/strong><\/p>\n<p>The <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-32977-unauthenticated-backup-file-upload-vulnerability-in-quest-kace-systems-management-appliance\/\"  data-wpil-monitor-id=\"64432\">vulnerability lies within the Form_Login file<\/a> and specifically targets the argument authCode\/goURL. The successful manipulation of this argument can lead to <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-32976-two-factor-authentication-bypass-vulnerability-in-quest-kace-systems-management-appliance\/\"  data-wpil-monitor-id=\"64311\">bypassing the authentication<\/a> process. This means that an attacker can gain <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-4855-unauthorized-access-vulnerability-in-support-board-plugin-for-wordpress\/\"  data-wpil-monitor-id=\"70969\">unauthorized access<\/a> to the system without needing any valid credentials. The attack, however, needs to be initiated from within the local network.<\/p>\n<p><strong>Conceptual Example Code<\/strong><\/p><div id=\"ameeb-2985489582\" 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>Below is a conceptual representation of how the vulnerability might be exploited. This does not represent an actual exploit but is <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-30419-memory-corruption-vulnerability-in-ni-circuit-design-suite\/\"  data-wpil-monitor-id=\"68175\">designed to illustrate the potential danger of the vulnerability<\/a>.<\/p>\n<pre><code class=\"\" data-line=\"\">POST \/formLoginAuth.htm HTTP\/1.1\nHost: target.example.com\nContent-Type: application\/x-www-form-urlencoded\nauthCode=anyvalue&amp;goURL=anyvalue<\/code><\/pre>\n<p>In this example, the attacker replaces the &#8216;authCode&#8217; and &#8216;goURL&#8217; parameters with arbitrary values, potentially <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2024-52928-severe-bypass-issue-in-arc-on-windows-allows-unauthorized-permissions-grant\/\"  data-wpil-monitor-id=\"65074\">bypassing the security checks in place and gaining unauthorized<\/a> access.<\/p>\n<p><strong>Mitigation and Workaround<\/strong><\/p>\n<p>As a mitigation measure, users are advised to apply the vendor patch as soon as it is available. In the meantime, the use of a Web Application Firewall (WAF) or Intrusion Detection System (IDS) can serve as a temporary mitigation to prevent <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-6505-unauthorized-access-and-impersonation-vulnerability-in-progress-software-s-hybrid-data-pipeline-server\/\"  data-wpil-monitor-id=\"71404\">unauthorized access<\/a>. Regularly updating and patching systems, as well as implementing robust network security measures, can also help in reducing the <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-52709-high-risk-deserialization-of-untrusted-data-vulnerability-in-everest-forms\/\"  data-wpil-monitor-id=\"65244\">risk of such vulnerabilities<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Overview In the world of cybersecurity, few things are as unsettling as the discovery of a critical vulnerability. And that&#8217;s exactly what we&#8217;re dealing with in the case of CVE-2025-6916, a troubling flaw in the TOTOLINK T6 4.1.5cu.748_B20211015. This vulnerability affects a crucial function of the Form_Login file, specifically the manipulation of the authCode\/goURL argument, [&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":[1],"tags":[],"vendor":[],"product":[],"attack_vector":[75],"asset_type":[],"severity":[],"exploit_status":[],"class_list":["post-57780","post","type-post","status-publish","format-standard","hentry","category-uncategorized","attack_vector-authentication-bypass"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/posts\/57780","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=57780"}],"version-history":[{"count":11,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/posts\/57780\/revisions"}],"predecessor-version":[{"id":63845,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/posts\/57780\/revisions\/63845"}],"wp:attachment":[{"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/media?parent=57780"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/categories?post=57780"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/tags?post=57780"},{"taxonomy":"vendor","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/vendor?post=57780"},{"taxonomy":"product","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/product?post=57780"},{"taxonomy":"attack_vector","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/attack_vector?post=57780"},{"taxonomy":"asset_type","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/asset_type?post=57780"},{"taxonomy":"severity","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/severity?post=57780"},{"taxonomy":"exploit_status","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/exploit_status?post=57780"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}