CVE-2026-7490

Executive Summary

CVE-2026-7490 is an arbitrary file upload vulnerability affecting the Sunnet CTMS (Competency Training Management System) and CPAS (Competency Profile Analysis System) web applications. A privileged remote attacker can exploit this flaw to upload malicious web shell backdoors to the server, achieving arbitrary code execution with the privileges of the web application process. The vulnerability carries a CVSS score of 8.6 (High severity), indicating significant risk of full server compromise. Affected organizations are primarily in the education and training sector within Taiwan, where these applications are widely deployed.

Technical Analysis

CVE-2026-7490 is classified under CWE-434 (Unrestricted Upload of File with Dangerous Type). The vulnerability resides in the file upload functionality of both CTMS and CPAS, developed by Sunnet. While the exact vulnerable endpoint is not publicly documented due to the limited information available in the CNA disclosure, the vulnerability class allows us to infer the underlying mechanism.

Vulnerability Mechanism:

The file upload handlers in both applications fail to properly validate:

1. File extension — The server does not restrict uploads to safe file types (e.g., images, documents). An attacker can upload .jsp, .jspx, .php, or other executable extensions.
2. File content — No content-based validation (MIME sniffing or magic byte checking) is performed to verify the file is what it claims to be.
3. Storage location — Whether uploaded files are stored within the web application's document root, making them directly accessible and executable via a web request.

Given these applications are likely Java-based (common in Taiwanese government/education systems and consistent with JSP web shell usage), a typical attack would involve uploading a JSP web shell. The server-side code likely uses naive logic such as:

// Vulnerable pseudocode
String fileName = request.getParameter("uploadFile");
String saveDir = "/var/www/html/uploads/";
File uploadedFile = new File(saveDir + fileName);
filePart.write(uploadedFile.getAbsolutePath());

Without extension whitelisting, content-type verification, or directory segregation outside the web root, the uploaded JSP file becomes a weaponized endpoint accessible via HTTP.

Attack Surface:

• Authentication Required: Privileged account access is required, meaning an attacker needs valid credentials for an administrative or high-privilege role within CTMS or CPAS.
• Network Exposure: The applications are web-based and typically exposed via HTTP/HTTPS on standard ports (80/443).
• Privilege Context: Executed code runs with the privileges of the web application server (typically tomcat, jboss, or similar), which if not sandboxed, may have broad system access.

Affected Scope: No specific version numbers are listed in the CVE data, meaning all versions of CTMS and CPAS up to the point of the vendor patch are presumed vulnerable.

Exploitation Scenarios

Prerequisites: Valid privileged account credentials (administrator-level role) for either CTMS or CPAS.

Step 1 — Reconnaissance and Target Identification

An attacker performs internet-wide or targeted scanning for Sunnet CTMS/CPAS instances. Using search dorks, the attacker identifies exposed login portals. The attacker then leverages credential stuffing, phishing, or previous breaches of the organization to obtain privileged credentials. Alternatively, if weak default credentials exist for administrator accounts, these may be attempted directly.

Step 2 — Authentication and Navigation to Upload Functionality

The attacker authenticates to the CTMS/CPAS web portal using the compromised privileged account. They navigate to a functional area that provides file upload capabilities — commonly found in modules for:

• Course material uploads (syllabi, training manuals)
• User profile image uploads
• Certificate/document attachment uploads
• Batch data import tools

The attacker identifies the upload form and inspects the file input field, noting the target endpoint path (e.g., /ctms/uploadHandler.jsp or /cpas/api/file/upload).

Step 3 — Weaponization and Payload Upload

The attacker crafts a JSP web shell with arbitrary code execution capability. A minimal example:

<% 
Runtime.getRuntime().exec(request.getParameter("cmd"));
%>

The attacker renames the file to shell.jsp (or disguises it as avatar.jpg.jsp to bypass weak extension filters). The file is uploaded via the browser or a tool like curl:

curl -X POST -F "file=@shell.jsp" -F "sessionId=<valid_session>" http://target/ctms/upload

Step 4 — Triggering the Web Shell

The attacker locates the uploaded file's URL path on the server, typically predictable: http://target/ctms/uploads/shell.jsp. Accessing this URL executes the JSP code server-side. The attacker now has arbitrary command execution:

http://target/ctms/uploads/shell.jsp?cmd=id

Step 5 — Post-Exploitation

With code execution established, the attacker:

• Escalates privileges to root/administrator via kernel exploits or misconfigured sudo/setuid binaries.
• Exfiltrates the SQL database containing student/trainee PII, login credentials, and training records.
• Establishes persistence via cron jobs, new admin accounts, or SSH backdoors.
• Pivots laterally into the internal network, using the compromised server as a foothold.

Impact Assessment

CVSS Analysis (8.6 High):

The CVSS vector (while specific values are undisclosed) indicates high ratings across key metrics — likely reflecting:

• Attack Complexity: Low — No special conditions needed beyond valid credentials.
• Privileges Required: High — Requires privileged account, but the impact is catastrophic.
• Confidentiality/Integrity/Availability Impact: High — Full server compromise enables data theft, data modification, and denial of service.

Business Impact:

• Data Breach: CTMS/CPAS systems store sensitive personal data of trainees, including identification numbers, academic records, certifications, and potentially health information depending on the training domain.
• Regulatory Consequences: Organizations processing personal data may face penalties under Taiwan's Personal Data Protection Act (PDPA).
• Operational Disruption: An attacker with web shell access can destroy data, deface portals, or encrypt systems (ransomware).

Blast Radius:

• Direct Systems: The CTMS/CPAS server and its database.
• Connected Systems: Integration with LDAP/AD for single sign-on means credential theft could cascade to the entire domain.
• Sector Impact: Education and vocational training sectors; if deployed across multiple institutions, a single vulnerability enables supply-chain style attacks across the sector.

Exploitation Likelihood: EPSS score of 0.00465 (37.9th percentile) suggests low-to-moderate active exploitation probability. CISA KEV does not list this CVE, indicating no confirmed in-the-wild exploitation as of the report date.

Detection Guidance

Sigma Rule

title: Sunnet CTMS/CPAS - Suspicious File Upload
id: e4c3a2b1-9f88-4d55-aabb-1234567890ab
status: experimental
description: Detects uploads of executable file types (JSP, JSPX, PHP, ASPX) to Sunnet CTMS/CPAS web applications
author: Valtersit Threat Intelligence
date: 2026/01/15
tags:
    - attack.t1190
    - attack.t1505.003
    - cve.2026.7490
logsource:
    category: webserver
    product: apache
    definition: Requires web server access logs for the CTMS/CPAS application
detection:
    selection:
        cs-uri-extension:
            - '.jsp'
            - '.jspx'
            - '.php'
            - '.phtml'
            - '.asp'
            - '.aspx'
        cs-uri-stem:
            - '*upload*'
            - '*import*'
            - '*attachment*'
    condition: selection
level: high
falsepositives:
    - Legitimate administrators uploading JSP files for development purposes (rare)
fields:
    - c-ip
    - cs-uri-stem
    - sc-status
    - cs-user-agent

YARA Rule

rule Sunnet_CTMS_CPAS_WebShell_Upload
{
    meta:
        author = "Valtersit Threat Intelligence"
        description = "Detects JSP web shell payloads targeting Sunnet CTMS/CPAS arbitrary file upload vulnerability"
        cve = "CVE-2026-7490"
        date = "2026-01-15"
        severity = "high"

    strings:
        $jsp_marker = "Runtime.getRuntime().exec"
        $jsp_marker2 = "ProcessBuilder"
        $jsp_marker3 = "getParameter(\"cmd\")"
        $jsp_marker4 = "getParameter(\"command\")"
        $jsp_marker5 = "java.io.InputStream"
        $suspicious_ext = ".jsp" 
        $webshell_name = "shell.jsp"
        $webshell_name2 = "cmd.jsp"
        $import_java1 = "import java.io.*"
        $import_java2 = "import javax.servlet.*"
        $exec_method = "exec("

    condition:
        uint32be(0) == 0xEFBBBF or uint32be(0) == 0xFFFE or
        filesize < 500KB and
        (
            all of ($jsp_marker*)
            or ($exec_method and any of ($import_java*))
            or ($suspicious_ext and any of ($webshell_name*))
        )
}

Suricata IDS Rule

alert http any any -> $HOME_NET any (
    msg:"CVE-2026-7490 - Sunnet CTMS/CPAS Arbitrary File Upload Attempt";
    flow:to_server,established;
    http.method:"POST";
    http.uri:contains"/upload";
    http.request_body; content:"filename="; nocase;
    http.request_body; content:".jsp"; nocase;
    http.request_body; content:"Content-Type"; nocase;
    sid:20267490;
    rev:1;
    classtype:web-application-attack;
    reference:cve,2026-7490;
    metadata:attack_target Web_Server;
)

Elastic Detection

sequence by host.name with maxspan=30s
  [ process where event.action == "file-create" and 
    file.extension in ("jsp", "jspx", "php", "phtml", "asp", "aspx") and
    file.path : ("*ctms*", "*cpas*", "*sunnet*", "*upload*") ]
  [ network where event.action == "http_request" and 
    http.request.method == "POST" and
    http.request.uri : ("*upload*", "*import*", "*attachment*") ]

Splunk SPL Query

index=web sourcetype=iis:log OR sourcetype=access_combined
| search method=POST
| search uri_path IN ("*upload*", "*import*", "*attachment*")
| search uri_path IN ("*.jsp", "*.jspx", "*.php", "*.phtml", "*.asp", "*.aspx") 
    OR (file_name IN ("*.jsp", "*.jspx", "*.php"))
| stats count by src_ip, uri_path, status, host
| table _time, src_ip, host, uri_path, file_name, status, count
| sort - _time

Wazuh OSSEC Rule

<rule id="100392" level="12">
    <if_sid>31510</if_sid>
    <field name="url">\.(jsp|jspx|php|phtml|asp|aspx)$</field>
    <field name="method">POST</field>
    <description>CVE-2026-7490 - Sunnet CTMS/CPAS arbitrary file upload attempt (JSP/PHP shell)</description>
    <group>web_application_attack,</group>
    <mitre>
        <id>T1190</id>
    </mitre>
</rule>

<rule id="100393" level="15">
    <if_sid>100392</if_sid>
    <field name="url">upload|import|attachment</field>
    <description>CVE-2026-7490 - Confirmed file upload to vulnerable CTMS/CPAS endpoint</description>
    <group>web_application_attack,</group>
</rule>

Mitigation & Patch Guidance

Patch Confidence: 2/4 (CLAIMED — single source, the CNA, claims a patch exists; not independently verified).

1. Immediate Mitigations (Until Patch Verification)

• Restrict Access: Implement network restrictions to limit CTMS/CPAS administrative interfaces to authorized IP ranges or VPN access only.
• Disable Unused Upload Functionality: If file upload modules are not actively used, disable them at the web server level (e.g., Apache mod_rewrite to reject POST requests to known upload endpoints).
• Monitor Administrative Accounts: Enable enhanced logging and alerting for privileged account logins and any file upload activity.
• Web Application Firewall (WAF): Deploy WAF rules to block uploads of executable file extensions (.jsp, .php, etc.) to these applications.

2. Patch/Upgrade Steps

• Contact Sunnet Technical Support to request the latest security patch for CTMS and CPAS.
• Verify the patch version received matches the official release; cross-reference with Sunnet's advisory before deployment.
• Stage the patch in a non-production environment first to validate compatibility.
• Schedule a maintenance window for deployment to production.
• After patching, verify the file upload functionality now rejects dangerous file types.

3. Long-Term Hardening

• Configuration Review: Ensure the web application server (Tomcat/JBoss) is hardened: disable directory listing, restrict upload directories outside the document root.
• Input Validation: Request Sunnet to implement extension whitelisting, MIME-type validation, and content-based inspection on all uploads.
• Least Privilege: Review all privileged accounts and remove those not actively needed. Implement MFA for all administrative access.
• Segmentation: Place CTMS/CPAS in a DMZ or isolated network segment with no direct routing to the core corporate network.
• Backup Verification: Ensure regular, tested backups are in place for rapid recovery in the event of compromise.
• Vulnerability Scanning: Add these applications to routine vulnerability scanning schedules to detect regression or incomplete patching.

References

1. NVD Entry: https://nvd.nist.gov/vuln/detail/CVE-2026-7490 — National Vulnerability Database entry with official description and CVSS scoring.
2. TWCERT/CC Advisory: https://www.twcert.org.tw/ — Taiwan Computer Emergency Response Team coordination center; the originating CNA publishing details on Sunnet CTMS/CPAS vulnerabilities.
3. CWE-434 Reference: https://cwe.mitre.org/data/definitions/434.html — Unrestricted Upload of File with Dangerous Type, the underlying weakness class.
4. MITRE ATT&CK — T1505.003: https://attack.mitre.org/techniques/T1505/003/ — Web Shell technique for post-compromise persistence via uploaded malicious content.
5. CISA Known Exploited Vulnerabilities Catalog: https://www.cisa.gov/news-events/alerts — CVE not present on the KEV list as of this reporting date; monitor this catalog for changes if exploitation is confirmed.

Threat Actor Activity: No known threat actor campaigns have been publicly attributed to this CVE as of the reporting date, and it is not listed in the CISA KEV, indicating no confirmed in-the-wild exploitation. However, the high CVSS score and the sensitive nature of data handled by CTMS/CPAS make this an attractive target for opportunistic attackers and advanced persistent threat groups operating in the Asia-Pacific region. Security teams should monitor their environments for the detection patterns described above.