CVE-2026-30404: Wgstart Wgcloud SSRF Vulnerability

CVE-2026-30404 Overview

CVE-2026-30404 is a Server-Side Request Forgery (SSRF) vulnerability in WGCLOUD v3.6.3. The flaw resides in the backend database management connection test feature. Attackers can abuse this feature to make the server issue arbitrary outbound requests. This enables internal network reconnaissance, retrieval of internal-only resources, and remote download of malicious files. The vulnerability is tracked under [CWE-918] (Server-Side Request Forgery).

The issue is exploitable over the network without authentication or user interaction. Successful exploitation impacts confidentiality by exposing internal services that would otherwise be unreachable from the public internet.

Critical Impact
An unauthenticated remote attacker can coerce the WGCLOUD server into probing internal network resources and downloading attacker-controlled content via the database connection test endpoint.

Affected Products

WGCLOUD v3.6.3 (wgstart:wgcloud)
Backend database management module
Database connection test feature

Discovery Timeline

2026-03-19 - CVE-2026-30404 published to NVD
2026-04-02 - Last updated in NVD database

Technical Details for CVE-2026-30404

Vulnerability Analysis

WGCLOUD is an open-source monitoring platform for servers, databases, and network devices. The backend administrative interface includes a database management module that allows operators to test database connectivity before saving credentials. The connection test accepts a user-supplied host and port intended to target a database endpoint.

The vulnerability stems from the absence of validation on the destination address used during the connection test. The server initiates a network connection to whatever host and port the request specifies. An attacker can substitute internal IP addresses, loopback interfaces, cloud metadata endpoints, or external attacker-controlled hosts. The server then performs the request on behalf of the attacker, exposing internal-only services and enabling retrieval of remote payloads.

This matches the classic SSRF pattern described by [CWE-918], where the server acts as a confused deputy. The impact is limited to confidentiality under the recorded CVSS metrics, but in practice SSRF often serves as a stepping stone for lateral movement or credential theft from metadata services.

Root Cause

The root cause is missing destination allowlisting in the database connection test handler. The endpoint does not restrict targets to known database hosts. It also does not block requests to private address ranges, link-local addresses, or loopback addresses. No protocol or scheme filtering is applied to prevent abuse beyond standard database protocols.

Attack Vector

An attacker submits a crafted database connection test request through the backend interface. The host parameter is set to an internal IP, a cloud instance metadata IP such as 169.254.169.254, or an attacker-controlled server. The WGCLOUD backend then opens a connection to that destination. Response timing and error content can reveal whether the internal service exists, effectively turning the endpoint into a port scanner and file fetcher.

The vulnerability is described in prose because no verified proof-of-concept code is published in the referenced advisories. Refer to the GitHub Issue #98 Report and the GitHub Issue #3 Discussion for the original reports.

Detection Methods for CVE-2026-30404

Indicators of Compromise

Outbound connections from the WGCLOUD backend host to private IP ranges (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16) that do not match known database servers.
Outbound requests from WGCLOUD to cloud metadata endpoints such as 169.254.169.254.
Repeated database connection test requests in WGCLOUD application logs with varying host and port values.
Unexpected outbound HTTP or TCP traffic from the WGCLOUD process to internet hosts during connection test operations.

Detection Strategies

Monitor WGCLOUD application logs for the database connection test endpoint and alert on non-database destination ports.
Inspect egress traffic from the WGCLOUD server and flag connections to RFC1918 ranges, link-local ranges, and metadata service IPs.
Correlate authentication events on the WGCLOUD admin interface with subsequent outbound connection attempts to detect abuse patterns.

Monitoring Recommendations

Deploy network egress filtering on the WGCLOUD host and log all denied connection attempts for triage.
Forward WGCLOUD backend logs and host network telemetry to a centralized analytics platform for sustained review.
Track administrative session activity for anomalous use of the database management module outside scheduled maintenance windows.

How to Mitigate CVE-2026-30404

Immediate Actions Required

Restrict access to the WGCLOUD backend interface to trusted administrative networks only, using firewall rules or a VPN gateway.
Block outbound connections from the WGCLOUD server to internal subnets, loopback, and cloud metadata IPs that are not required for monitoring functions.
Audit recent WGCLOUD database connection test activity for suspicious destination hosts or ports.
Rotate any credentials that may have been exposed through cloud metadata services if SSRF abuse is suspected.

Patch Information

No vendor patch is referenced in the NVD entry for CVE-2026-30404 at the time of publication. Track the upstream project for an updated WGCLOUD release that addresses the connection test endpoint. Review the GitHub Issue #98 Report for vendor response and remediation status.

Workarounds

Place the WGCLOUD backend behind a reverse proxy that enforces authentication and IP allowlisting for administrative paths.
Apply host-based egress controls that allow the WGCLOUD process to reach only approved database endpoints.
Disable or remove the database management module if it is not in active use.
Run the WGCLOUD service under a network namespace or container with restricted outbound routing.

bash

# Example egress restriction using iptables on the WGCLOUD host
# Allow only approved database targets, drop everything else from the wgcloud user
sudo iptables -A OUTPUT -m owner --uid-owner wgcloud -d 10.20.30.40 -p tcp --dport 3306 -j ACCEPT
sudo iptables -A OUTPUT -m owner --uid-owner wgcloud -d 169.254.169.254 -j DROP
sudo iptables -A OUTPUT -m owner --uid-owner wgcloud -d 10.0.0.0/8 -j DROP
sudo iptables -A OUTPUT -m owner --uid-owner wgcloud -d 172.16.0.0/12 -j DROP
sudo iptables -A OUTPUT -m owner --uid-owner wgcloud -d 192.168.0.0/16 -j DROP