{"id":33997,"date":"2025-05-01T00:14:09","date_gmt":"2025-05-01T00:14:09","guid":{"rendered":""},"modified":"2025-06-17T11:20:11","modified_gmt":"2025-06-17T17:20:11","slug":"cve-2025-31478-zulip-server-vulnerability-allowing-unauthorized-account-creation","status":"publish","type":"post","link":"https:\/\/www.ameeba.com\/blog\/cve-2025-31478-zulip-server-vulnerability-allowing-unauthorized-account-creation\/","title":{"rendered":"<strong>CVE-2025-31478: Zulip Server Vulnerability Allowing Unauthorized Account Creation<\/strong>"},"content":{"rendered":"<p><strong>Overview<\/strong><\/p>\n<p>The Common Vulnerabilities and Exposures (CVE) system has recently identified a significant vulnerability, tagged as CVE-2025-31478, in the Zulip team collaboration tool. This open-source software facilitates team collaboration, but it is currently suffering from a notable bug that allows the creation of unauthorized accounts. This <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-41646-critical-authentication-bypass-vulnerability-in-affected-software-packages\/\"  data-wpil-monitor-id=\"59324\">vulnerability specifically affects<\/a> organizations that use Zulip and have disabled the EmailAuthBackend, thus relying on Single Sign-On (SSO) authentication. The issue is critical as it can lead to potential <a href=\"https:\/\/www.ameeba.com\/blog\/yale-new-haven-health-system-data-breach-a-comprehensive-analysis-of-a-cybersecurity-breach-impacting-5-5-million-patients\/\"  data-wpil-monitor-id=\"38817\">system compromise or data<\/a> leakage, thereby posing severe threats to the security and privacy of the affected organizations.<\/p>\n<p><strong>Vulnerability Summary<\/strong><\/p>\n<p>CVE ID: CVE-2025-31478<br \/>\nSeverity: High (CVSS: 8.2)<br \/>\nAttack Vector: Network<br \/>\nPrivileges Required: None<br \/>\nUser Interaction: None<br \/>\nImpact: System compromise or <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2023-50612-escalation-of-privileges-and-data-leakage-in-fit2cloud-cloud-explorer-lite\/\"  data-wpil-monitor-id=\"41287\">data leakage<\/a><\/p>\n<p><strong>Affected Products<\/strong><\/p><div id=\"ameeb-1341472500\" 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>Zulip Server | Prior to 10.2<\/p>\n<p><strong>How the Exploit Works<\/strong><\/p>\n<p>The <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-32834-exploiting-telecontrol-server-basic-via-sql-injection\/\"  data-wpil-monitor-id=\"38816\">exploit takes advantage of a flaw in the Zulip server&#8217;s<\/a> authentication system. Specifically, when the EmailAuthBackend is disabled, Zulip relies on SSO authentication. However, the bug allows an attacker to bypass this SSO requirement and create an <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2023-44752-authentication-bypass-vulnerability-in-student-study-center-desk-management-system\/\"  data-wpil-monitor-id=\"40350\">account<\/a> without an SSO authenticated backend. This unauthorized account creation can potentially grant an attacker <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-28233-incorrect-access-control-vulnerability-in-bw-broadcast-hardware\/\"  data-wpil-monitor-id=\"38518\">access to sensitive data or control<\/a> over the compromised system.<\/p>\n<p><strong>Conceptual Example Code<\/strong><\/p><div id=\"ameeb-364311034\" 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>In a conceptual scenario, an attacker may send a HTTP POST request to the Zulip server&#8217;s <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-46275-unauthenticated-account-creation-vulnerability-in-wgs-80hpt-v2-and-wgs-4215-8t2s\/\"  data-wpil-monitor-id=\"41513\">account creation<\/a> endpoint. The malicious request might look something like this:<\/p>\n<pre><code class=\"\" data-line=\"\">POST \/api\/v1\/accounts\/create HTTP\/1.1\nHost: zulip-vulnerable-server.com\nContent-Type: application\/json\n{\n&quot;email&quot;: &quot;attacker@malicious.com&quot;,\n&quot;password&quot;: &quot;password123&quot;,\n&quot;realm&quot;: &quot;org_zulip&quot;\n}<\/code><\/pre>\n<p>In this example, &#8220;attacker@malicious.com&#8221; is the email the attacker is trying to register, &#8220;password123&#8221; is the desired password, and &#8220;org_zulip&#8221; is the organization the attacker is attempting to infiltrate.<\/p>\n<p><strong>Workaround and Mitigation<\/strong><\/p>\n<p>The recommended mitigation for this vulnerability is to apply the vendor-supplied patch, which is included in Zulip Server version 10.2. In the interim, organizations can use a Web Application Firewall (WAF) or Intrusion Detection System (IDS) to help mitigate the vulnerability. Additionally, requiring invitations to join the organization can prevent the <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-47154-exploitation-of-use-after-free-vulnerability-in-libjs-in-ladybird\/\"  data-wpil-monitor-id=\"59325\">vulnerability from being exploited<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Overview The Common Vulnerabilities and Exposures (CVE) system has recently identified a significant vulnerability, tagged as CVE-2025-31478, in the Zulip team collaboration tool. This open-source software facilitates team collaboration, but it is currently suffering from a notable bug that allows the creation of unauthorized accounts. This vulnerability specifically affects organizations that use Zulip and have [&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":[],"asset_type":[],"severity":[],"exploit_status":[],"class_list":["post-33997","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/posts\/33997","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=33997"}],"version-history":[{"count":6,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/posts\/33997\/revisions"}],"predecessor-version":[{"id":53016,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/posts\/33997\/revisions\/53016"}],"wp:attachment":[{"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/media?parent=33997"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/categories?post=33997"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/tags?post=33997"},{"taxonomy":"vendor","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/vendor?post=33997"},{"taxonomy":"product","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/product?post=33997"},{"taxonomy":"attack_vector","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/attack_vector?post=33997"},{"taxonomy":"asset_type","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/asset_type?post=33997"},{"taxonomy":"severity","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/severity?post=33997"},{"taxonomy":"exploit_status","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/exploit_status?post=33997"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}