CVE-2026-30839: Wallosapp Wallos SSRF Vulnerability

CVE-2026-30839 Overview

CVE-2026-30839 is a Server-Side Request Forgery (SSRF) vulnerability affecting Wallos, an open-source, self-hostable personal subscription tracker. Prior to version 4.6.2, the testwebhooknotifications.php endpoint does not validate the target URL against private or reserved IP ranges, enabling full-read SSRF attacks. The server response is returned directly to the caller, allowing attackers to read internal resources and potentially access sensitive information from the internal network.

Critical Impact

Authenticated attackers can leverage this SSRF vulnerability to access internal services, read sensitive data from cloud metadata endpoints, and potentially pivot to other systems within the internal network.

Affected Products

• Wallos versions prior to 4.6.2
• wallosapp wallos (all versions before the security patch)
• Self-hosted Wallos instances running vulnerable versions

Discovery Timeline

• 2026-03-07 - CVE-2026-30839 published to NVD
• 2026-03-11 - Last updated in NVD database

Technical Details for CVE-2026-30839

Vulnerability Analysis

This vulnerability is classified as CWE-918 (Server-Side Request Forgery), a web application vulnerability that allows attackers to induce the server-side application to make HTTP requests to an arbitrary domain of the attacker's choosing. In the case of CVE-2026-30839, the testwebhooknotifications.php file in Wallos accepts user-supplied URLs for webhook testing functionality without implementing proper validation against private, reserved, or localhost IP address ranges.

The vulnerability enables authenticated users to craft malicious requests that cause the Wallos server to make outbound HTTP requests to internal network resources. Because the full server response is returned to the caller, this constitutes a "full-read" SSRF, which is particularly dangerous as it allows exfiltration of sensitive data from internal services.

Root Cause

The root cause of this vulnerability lies in the absence of URL validation within the testwebhooknotifications.php endpoint. The application accepts user-supplied webhook URLs and makes requests to them without checking whether the target IP address falls within:

• Private IP ranges (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16)
• Localhost addresses (127.0.0.0/8)
• Link-local addresses (169.254.0.0/16)
• Reserved or special-purpose IP ranges

This missing input validation allows attackers to bypass network segmentation and access internal services that should not be reachable from external networks.

Attack Vector

The attack vector is network-based and requires low-privilege authentication to access the webhook testing functionality. An authenticated attacker can exploit this vulnerability by:

1. Accessing the vulnerable testwebhooknotifications.php endpoint
2. Supplying a crafted URL pointing to internal resources (e.g., cloud metadata services at 169.254.169.254, internal APIs, or localhost services)
3. The Wallos server makes the request on behalf of the attacker
4. The full response from the internal resource is returned to the attacker

This attack pattern can be used to access cloud instance metadata endpoints, internal APIs, administrative interfaces, and other services not exposed to the public internet. The vulnerability mechanism involves insufficient URL validation allowing requests to internal network addresses. For detailed technical information, refer to the GitHub Security Advisory GHSA-x4qp-xm2c-vqg9.

Detection Methods for CVE-2026-30839

Indicators of Compromise

• Unusual outbound HTTP requests from the Wallos server to internal IP addresses or cloud metadata endpoints
• Access logs showing requests to testwebhooknotifications.php with suspicious URL parameters containing internal IP addresses
• Network traffic from the Wallos server to 169.254.169.254 (AWS/GCP metadata) or other cloud provider metadata services
• Requests targeting internal services on ports typically associated with databases, caches, or administrative interfaces

Detection Strategies

• Monitor web server access logs for requests to testwebhooknotifications.php containing private IP addresses or localhost references in URL parameters
• Implement network-level monitoring to detect outbound connections from the Wallos application to internal network ranges
• Deploy web application firewall (WAF) rules to block requests containing internal IP addresses in webhook URL parameters
• Review authentication logs for accounts repeatedly testing webhooks with internal or unusual URLs

Monitoring Recommendations

• Enable detailed logging for the Wallos application and monitor for SSRF attack patterns
• Configure network segmentation and firewall rules to restrict outbound connections from the Wallos server to only necessary external services
• Implement egress filtering to prevent the application server from accessing internal network resources
• Set up alerts for any access to cloud metadata endpoints from application servers

How to Mitigate CVE-2026-30839

Immediate Actions Required

• Upgrade Wallos to version 4.6.2 or later immediately
• Review access logs for evidence of exploitation attempts against testwebhooknotifications.php
• Implement network-level controls to restrict outbound connections from the Wallos server until patching is complete
• Audit any sensitive internal services that may have been accessed through SSRF exploitation

Patch Information

The vulnerability has been patched in Wallos version 4.6.2. The security fix is documented in the GitHub Commit Details. Users should upgrade to version 4.6.2 or later by downloading from the GitHub Release v4.6.2.

For additional context on this vulnerability, refer to the GitHub Security Advisory GHSA-x4qp-xm2c-vqg9.

Workarounds

• Implement a reverse proxy or WAF rule to filter requests to testwebhooknotifications.php containing internal IP addresses
• Disable the webhook testing functionality if not required by removing or restricting access to testwebhooknotifications.php
• Deploy network-level egress filtering to prevent the application from making requests to internal IP ranges
• Use firewall rules to restrict outbound HTTP requests from the Wallos server to a whitelist of known external services

# Example: Block outbound connections to internal IP ranges using iptables
# Apply these rules to the server running Wallos

# Block connections to private IPv4 ranges
iptables -A OUTPUT -d 10.0.0.0/8 -j DROP
iptables -A OUTPUT -d 172.16.0.0/12 -j DROP
iptables -A OUTPUT -d 192.168.0.0/16 -j DROP
iptables -A OUTPUT -d 127.0.0.0/8 -j DROP
iptables -A OUTPUT -d 169.254.0.0/16 -j DROP

# Note: Apply only to the Wallos application user/context
# Test thoroughly before production deployment