{"id":87140,"date":"2026-06-16T22:08:58","date_gmt":"2026-06-16T22:08:58","guid":{"rendered":""},"modified":"-0001-11-30T00:00:00","modified_gmt":"-0001-11-30T06:00:00","slug":"cve-2025-43979-arbitrary-os-command-execution-vulnerability-in-firstnum-jc21a-04-devices","status":"publish","type":"post","link":"https:\/\/www.ameeba.com\/blog\/cve-2025-43979-arbitrary-os-command-execution-vulnerability-in-firstnum-jc21a-04-devices\/","title":{"rendered":"<strong>CVE-2025-43979: Arbitrary OS Command Execution Vulnerability in FIRSTNUM JC21A-04 Devices<\/strong>"},"content":{"rendered":"<p><strong>Overview<\/strong><\/p>\n<p>This report covers the analysis of a critical vulnerability identified in FIRSTNUM JC21A-04 devices. The discovered issue, designated as CVE-2025-43979, enables authenticated attackers to execute arbitrary operating system commands with root privileges. Given the severity of the vulnerability, it&#8217;s imperative for all users of these devices to take immediate measures to mitigate its potential impact.<\/p>\n<p><strong>Vulnerability Summary<\/strong><\/p>\n<p>CVE ID: CVE-2025-43979<br \/>\nSeverity: High (CVSS: 7.4)<br \/>\nAttack Vector: Network<br \/>\nPrivileges Required: Low (Authentication required)<br \/>\nUser Interaction: None<br \/>\nImpact: System compromise or data leakage<\/p>\n<p><strong>Affected Products<\/strong><\/p><div id=\"ameeb-844233098\" 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>FIRSTNUM JC21A-04 | Up to and including 2.01ME\/FN<\/p>\n<p><strong>How the Exploit Works<\/strong><\/p>\n<p>The exploit takes advantage of a vulnerability in the xml_action.cgi?method= endpoint of FIRSTNUM JC21A-04 devices. By sending a crafted payload to this endpoint, an authenticated attacker is capable of executing arbitrary operating system commands with root privileges, allowing them to gain complete control over the affected system or access sensitive data.<\/p>\n<p><strong>Conceptual Example Code<\/strong><\/p><div id=\"ameeb-142122356\" 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 example of a malicious HTTP request exploiting this vulnerability:<\/p>\n<pre><code class=\"\" data-line=\"\">POST \/xml_action.cgi?method= HTTP\/1.1\nHost: target_device_ip\nContent-Type: application\/json\nAuthorization: Basic base64_auth_string\n{\n&quot;command&quot;: &quot;malicious_os_command&quot;\n}<\/code><\/pre>\n<p>In this example, `base64_auth_string` is the base64 encoded string of the attacker&#8217;s username and password, and `malicious_os_command` is the OS command that the attacker wants to execute with root privileges.<\/p>\n<p><strong>Mitigation<\/strong><\/p>\n<p>Users are advised to apply the latest vendor patch to remediate this vulnerability. If a patch is not immediately available, users can employ a Web Application Firewall (WAF) or Intrusion Detection System (IDS) as a temporary mitigation measure. This vulnerability underlines the importance of continually monitoring for and applying security updates to all systems and devices.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Overview This report covers the analysis of a critical vulnerability identified in FIRSTNUM JC21A-04 devices. The discovered issue, designated as CVE-2025-43979, enables authenticated attackers to execute arbitrary operating system commands with root privileges. Given the severity of the vulnerability, it&#8217;s imperative for all users of these devices to take immediate measures to mitigate its potential [&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-87140","post","type-post","status-publish","format-standard","hentry"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/posts\/87140","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=87140"}],"version-history":[{"count":0,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/posts\/87140\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/media?parent=87140"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/categories?post=87140"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/tags?post=87140"},{"taxonomy":"vendor","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/vendor?post=87140"},{"taxonomy":"product","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/product?post=87140"},{"taxonomy":"attack_vector","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/attack_vector?post=87140"},{"taxonomy":"asset_type","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/asset_type?post=87140"},{"taxonomy":"severity","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/severity?post=87140"},{"taxonomy":"exploit_status","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/exploit_status?post=87140"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}