CISA Warns of Critical RCE Flaw (CVE-2025-10659, CVSS 9.8) in Megasys Telenium Online Web Application

The U.S. Cybersecurity and Infrastructure Security Agency (CISA) has issued a security advisory warning of a critical vulnerability in the Megasys Telenium Online Web Application that could lead to remote code execution (RCE) if exploited. Tracked as CVE-2025-10659, the flaw carries a CVSS v3.1 base score of 9.8, making it one of the most severe categories of vulnerabilities.

According to the advisory, “The Telenium Online Web Application is vulnerable due to a PHP endpoint accessible to unauthenticated network users that improperly handles user-supplied input. This vulnerability occurs due to the insecure termination of a regular expression check within the endpoint.”

Because the input is not properly sanitized, attackers can inject arbitrary operating system commands through a crafted HTTP request. “Successful exploitation of this vulnerability could allow an unauthenticated attacker to inject arbitrary operating system commands … leading to remote code execution on the server in the context of the web application service account.”

CISA confirmed that the following Megasys product is affected:

• Telenium Online Web Application: Versions 8.4.21 and prior

Megasys Enterprises has already provided a patch, and customers are urged to apply it immediately. Users should access the Megasys support page to get instructions on applying the fix

CISA also advises organizations to adopt standard defense-in-depth strategies to minimize the risk of exploitation:

• Minimize network exposure for all control system devices and/or systems, ensuring they are not accessible from the internet.
• Locate control system networks and remote devices behind firewalls and isolating them from business networks.
• When remote access is required, use more secure methods, such as Virtual Private Networks (VPNs), recognizing VPNs may have vulnerabilities and should be updated to the most current version available.

Related Posts:

• Urgent Security Alert: CISA Warns of Actively Exploited Apple and Microsoft Vulnerabilities
• CISA Adds 12 New Known Actively Exploited Vulnerabilities to its Catalog
• CISA Warns of Credential Risks Tied to Oracle Cloud Breach

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