{"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":"-0001-11-30T00:00:00","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":"CVE-2025-43979: Arbitrary OS Command Execution Vulnerability in FIRSTNUM JC21A-04 Devices<\/strong>"},"content":{"rendered":"

Overview<\/strong><\/p>\n

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’s imperative for all users of these devices to take immediate measures to mitigate its potential impact.<\/p>\n

Vulnerability Summary<\/strong><\/p>\n

CVE ID: CVE-2025-43979
\nSeverity: High (CVSS: 7.4)
\nAttack Vector: Network
\nPrivileges Required: Low (Authentication required)
\nUser Interaction: None
\nImpact: System compromise or data leakage<\/p>\n

Affected Products<\/strong><\/p>\n

Product | Affected Versions<\/p>\n

FIRSTNUM JC21A-04 | Up to and including 2.01ME\/FN<\/p>\n

How the Exploit Works<\/strong><\/p>\n

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

Conceptual Example Code<\/strong><\/p>\n

Below is a conceptual example of a malicious HTTP request exploiting this vulnerability:<\/p>\n

POST \/xml_action.cgi?method= HTTP\/1.1\nHost: target_device_ip\nContent-Type: application\/json\nAuthorization: Basic base64_auth_string\n{\n\"command\": \"malicious_os_command\"\n}<\/code><\/pre>\n
In this example, `base64_auth_string` is the base64 encoded string of the attacker’s username and password, and `malicious_os_command` is the OS command that the attacker wants to execute with root privileges.<\/p>\n
Mitigation<\/strong><\/p>\n
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":"
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’s imperative for all users of these devices to take immediate measures to mitigate its potential […]<\/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,"_monsterinsights_skip_tracking":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":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t