CVE-2025-59818

CriticalRCE

Published: 04 February 2026

Published

04 February 2026

Modified

11 February 2026

KEV Added

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Patch

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CVSS Score 10.0 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

EPSS Score 0.0015 34.7th percentile

Risk Priority 20 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2025-59818 is a critical-severity Command Injection (CWE-77) vulnerability in Zenitel Tcis-3 Firmware. Its CVSS base score is 10.0 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 34.7th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified are NIST 800-53 SI-10 (Information Input Validation) and SI-2 (Flaw Remediation).

Threat & Defense at a Glance

What attackers do: exploitation maps to Exploit Public-Facing Application (T1190) and 2 other techniques. What defenders deploy: see the NIST 800-53 controls recommended below.

Threat & Defense Details

Mitigating Controls (NIST 800-53 r5)AI

SI-10 Information Input Validation good match

prevent

Directly mitigates command injection by validating filenames of uploaded files to reject malicious payloads containing shell metacharacters.

SI-2 Flaw Remediation good match

prevent

Ensures timely remediation of the specific command injection flaw through patching to version 9.3 as recommended by the vendor.

SI-9 Information Input Restrictions partial match

prevent

Restricts filenames at file upload boundaries to safe character sets or patterns, blocking injection attempts via disallowed metacharacters.

MITRE ATT&CK Enterprise TechniquesAI

T1190 Exploit Public-Facing Application Initial Access

Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.

attack.mitre.org →

T1059 Command and Scripting Interpreter Execution

Adversaries may abuse command and script interpreters to execute commands, scripts, or binaries.

attack.mitre.org →

T1210 Exploitation of Remote Services Lateral Movement

Adversaries may exploit remote services to gain unauthorized access to internal systems once inside of a network.

attack.mitre.org →

Why these techniques?

Command injection via manipulated filename in file upload feature of network-accessible communication systems enables exploitation of public-facing applications (T1190) and remote services (T1210), directly facilitating arbitrary command execution (T1059).

Confidence: HIGH · MITRE ATT&CK Enterprise v19.0

NVD Description

This vulnerability allows authenticated attackers to execute arbitrary commands on the underlying system using the file name of an uploaded file.

Deeper analysisAI

CVE-2025-59818 is a command injection vulnerability (CWE-77) that enables authenticated attackers to execute arbitrary commands on the underlying system by manipulating the filename of an uploaded file. It affects Zenitel communication systems, including Turbine, VSF-Display Series, VSF-Fortitude6, VSF-Fortitude8, and ZIPS prior to version 9.3. The vulnerability carries a CVSS v3.1 base score of 10.0 (AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H), indicating critical severity with network accessibility, low attack complexity, no user interaction required, and full impacts on confidentiality, integrity, and availability in a changed scope.

An authenticated attacker, despite the CVSS indicating no privileges required (PR:N), can exploit this flaw by uploading a specially crafted file whose filename injects and executes arbitrary operating system commands. Successful exploitation grants remote code execution on the affected device, potentially leading to complete system compromise, data exfiltration, or further lateral movement within the network.

Zenitel's release notes for version 9.3 across the affected products—Turbine, VSF-Display Series, VSF-Fortitude6, VSF-Fortitude8, and ZIPS—address this vulnerability, recommending upgrade to the patched 9.3 release as the primary mitigation. No additional workarounds are detailed in the provided references.