CVE-2018-25411: SQL Injection in MGB OpenSource Guestbook 0.7.0.2 – Analysis & Remediation

Technical summary

CVE-2018-25411 is an unauthenticated SQL injection vulnerability in MGB OpenSource Guestbook 0.7.0.2 residing in the email.php endpoint. The 'id' GET parameter fails to properly sanitize or parameterize user input before incorporating it into SQL queries. An attacker can construct a malicious SQL payload in the 'id' parameter to extract database metadata and potentially sensitive records. The vulnerability is classified as CWE-89 (SQL Injection) and carries a CVSS v3.1 score of 8.2 (HIGH), reflecting high confidentiality impact and limited integrity risk. The attack vector is network-based with low complexity and requires no privileges or user interaction.

Business impact

A successful exploit enables attackers to enumerate the database schema and exfiltrate sensitive information such as user credentials, personal details, email addresses, or any other data stored in the Guestbook application's database. For organizations running older or legacy instances of this software, unauthorized data disclosure could violate privacy obligations, damage customer trust, and expose internal or user information to adversaries for secondary attacks. The ability to probe the database structure also facilitates further exploitation or lateral movement if the compromised system is part of a larger infrastructure.

Affected systems

MGB OpenSource Guestbook version 0.7.0.2 is vulnerable. Organizations running this legacy guestbook software—particularly older web applications or archived systems—are at direct risk. Because the vulnerability is unauthenticated and requires only network access to the affected endpoint, any publicly exposed instance of Guestbook 0.7.0.2 is immediately exploitable. Verify your inventory for this specific version; earlier or later versions may also require assessment pending vendor guidance.

Exploitability

Exploitability is very high. The attack requires only network access and a web browser or simple HTTP client; no authentication credentials, special privileges, or user interaction are necessary. A proof-of-concept exploitation is trivial—a single HTTP GET request with a SQL payload in the 'id' parameter will trigger the injection. The low complexity and minimal prerequisites mean that even unsophisticated attackers can quickly weaponize this vulnerability. No CISA KEV entry currently exists for this CVE, but the straightforward nature of the attack vector suggests active exploitation is likely if instances remain unpatched.

Remediation

Immediate action is required for any system running MGB OpenSource Guestbook 0.7.0.2. Verify with the MGB project or check their official repository for a patched version addressing CWE-89 SQL injection. If a patch is unavailable or the project is no longer maintained, consider retiring the application in favor of actively maintained alternatives. Apply input validation and parameterized queries (prepared statements) if in-house remediation is attempted. Restrict network access to the email.php endpoint using firewall rules or web application firewalls (WAF) as a temporary mitigation pending patching or replacement.

Patch guidance

Check the official MGB OpenSource Guestbook repository or vendor advisory for a patched release that addresses SQL injection in the email.php 'id' parameter. Patch version details must be verified against the vendor's official release notes. If the project is dormant, assess the feasibility of upgrading to a maintained alternative or decommissioning the application. Test any patch in a non-production environment before deployment. Verify that the patched version properly sanitizes all user inputs and uses parameterized queries.

Detection guidance

Monitor web server logs for suspicious GET requests to email.php containing SQL-like syntax in the 'id' parameter (e.g., single quotes, UNION statements, boolean logic, comment syntax). Deploy web application firewall (WAF) rules to detect and block SQL injection patterns. Database query logs should be reviewed for unusual queries or failed authentication attempts targeting system tables. Network intrusion detection systems (IDS) can be tuned to flag SQL injection signatures in HTTP traffic. If the application is publicly facing, consider implementing rate limiting and access controls to reduce the attack surface.

Why prioritize this

This vulnerability merits high priority due to the combination of high CVSS score (8.2), unauthenticated access, low attack complexity, and direct exposure of sensitive database information. The straightforward nature of exploitation and lack of barriers to weaponization increase the likelihood of active abuse if instances remain exposed. Legacy guestbook software running on production or semi-production systems poses an elevated risk, particularly if connected to networks holding sensitive data.

Risk score, explained

The CVSS v3.1 score of 8.2 (HIGH) reflects: (1) Network-based attack vector requiring no authentication; (2) Low attack complexity—standard SQL injection techniques apply; (3) High confidentiality impact—attackers can exfiltrate database contents; (4) Limited integrity and availability impact—the vulnerability primarily enables data disclosure rather than modification or denial of service. While not critical, the high score appropriately captures the severity for organizations relying on this application to protect user data.

Frequently asked questions