CVE-2026-27885

Executive Summary

CVE-2026-27885 is a critical SQL Injection vulnerability discovered in the Piwigo open-source photo gallery application, affecting versions prior to 16.3.0. The flaw resides in the Activity List API endpoint, allowing an authenticated administrator to execute arbitrary SQL queries against the backend database. This enables the extraction of sensitive data, including user credentials, email addresses, and all stored content. The vulnerability has been patched in version 16.3.0. Given the high privileges required (administrator), the CVSS score is 7.2 (High), but the potential impact is severe due to the complete compromise of confidentiality and integrity. No public proof-of-concept (PoC) or exploit code is currently available, but the risk remains significant for unpatched instances.

Supply Chain & Package Security

Piwigo is a PHP-based application distributed as a web package. The vulnerability is not in a dependency (NPM, PyPI, Go, Ruby) but in the core application code. The primary supply chain risk is the use of outdated or unmaintained Piwigo installations. Organizations should ensure they are using the official Piwigo source and verify the integrity of the downloaded package.

CVSS Breakdown & Threat Level

• CVSS Score: 7.2 (High)
• Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
• Attack Vector (AV): Network - The vulnerability can be exploited remotely over the network.
• Attack Complexity (AC): Low - No special conditions or complex attack sequences are required.
• Privileges Required (PR): High - An attacker must have valid administrator credentials.
• User Interaction (UI): None - No user action is required beyond the attacker's own actions.
• Scope (S): Unchanged - The vulnerable component and the impacted component are the same.
• Confidentiality (C): High - Complete disclosure of all database contents, including credentials and personal data.
• Integrity (I): High - Potential to modify or delete database records.
• Availability (A): High - Potential to disrupt database operations or delete data.

Threat Level: High. While the attack requires administrative privileges, the impact is catastrophic. An attacker who compromises an admin account (via phishing, credential stuffing, or other means) can fully compromise the database.

Deep Dive & Mechanics

The vulnerability is a classic SQL Injection flaw in the Activity List API endpoint. The endpoint likely accepts user-supplied parameters (e.g., sort, filter, limit, offset) that are directly concatenated into SQL queries without proper sanitization or parameterization.

Root Cause: The application fails to use prepared statements or parameterized queries when constructing SQL commands for the Activity List feature. Instead, it directly interpolates user input into the SQL string.

Attack Vector: An authenticated administrator sends a crafted HTTP request to the vulnerable API endpoint. The malicious payload is injected into one of the parameters, breaking out of the intended SQL syntax and allowing the attacker to execute arbitrary SQL commands.

Example (Conceptual): The vulnerable endpoint might be something like: /api/activity/list?sort=date&order=ASC

An attacker could modify the sort parameter to: /api/activity/list?sort=date; SELECT * FROM users--

If the application constructs the query as: SELECT * FROM activity_log ORDER BY [sort] [order]

The injected payload would result in: SELECT * FROM activity_log ORDER BY date; SELECT * FROM users-- ASC

This would execute the attacker's query and potentially return the contents of the users table.

Vulnerable vs. Patched Code

Vulnerable Code (Conceptual - Pre-16.3.0):

// Vulnerable: Direct string interpolation
$sort = $_GET['sort'];
$order = $_GET['order'];
$query = "SELECT * FROM activity_log ORDER BY $sort $order";
$result = mysqli_query($conn, $query);

Patched Code (Conceptual - 16.3.0):

// Patched: Using prepared statements and whitelisting
$allowedSortColumns = ['date', 'user', 'action'];
$sort = in_array($_GET['sort'], $allowedSortColumns) ? $_GET['sort'] : 'date';
$order = strtoupper($_GET['order']) === 'DESC' ? 'DESC' : 'ASC';
$query = "SELECT * FROM activity_log ORDER BY $sort $order";
// Alternatively, use parameterized queries for other parameters
$stmt = $conn->prepare("SELECT * FROM activity_log WHERE user = ?");
$stmt->bind_param("s", $user);
$stmt->execute();

The patched version implements input validation (whitelisting) for the sort and order parameters and uses prepared statements for other user-supplied data.

Exploitation & Lab Setup

Red Team (Offensive)

Prerequisites:

• A running instance of Piwigo version < 16.3.0.
• Valid administrator credentials (username and password).

Exploitation Steps:

1. Authenticate: Log in to the Piwigo admin panel.

2. Identify Endpoint: Locate the Activity List API endpoint. This is typically found at /api/activity/list or similar.

3. Craft Payload: Use a tool like curl or Burp Suite to send a crafted request. The exact parameter may vary, but a common injection point is the sort parameter.

   # Example using curl
   curl -c cookies.txt -b cookies.txt -X GET "http://target-piwigo.com/api/activity/list?sort=date;SELECT%20*%20FROM%20piwigo_users--"
   

4. Extract Data: The response may contain the results of the injected query. Use UNION-based or error-based techniques to extract data.

   -- UNION-based injection to extract user credentials
   sort=date UNION SELECT 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{/* [Security Hash: ED6A4F58D5FC2F8C2805F497] */}