CVE-2026-26745: OpenSourcePOS SQL Injection Vulnerability

CVE-2026-26745 Overview

CVE-2026-26745 is a second-order SQL injection vulnerability in OpenSourcePOS 3.4.1, an open source point of sale web application. The flaw resides in the handling of the currency_symbol configuration field. Although the application stores the value without immediately executing it, the field is later concatenated into a dynamically constructed SQL query without sanitization or parameter binding. An authenticated attacker who can modify the currency_symbol value can inject arbitrary SQL expressions that execute when the affected query runs. The vulnerability is tracked under CWE-89: Improper Neutralization of Special Elements used in an SQL Command.

Critical Impact

Authenticated attackers with access to modify configuration settings can extract sensitive database contents through deferred SQL execution.

Affected Products

• OpenSourcePOS Open Source Point of Sale 3.4.1
• Deployments using the currency_symbol configuration field
• Any downstream forks of OpenSourcePOS 3.4.1 that retain the vulnerable query construction

Discovery Timeline

• 2026-02-20 - CVE-2026-26745 published to NVD
• 2026-02-24 - Last updated in NVD database

Technical Details for CVE-2026-26745

Vulnerability Analysis

The vulnerability is a stored, second-order SQL injection. Unlike classic SQL injection, the malicious payload is not executed at the point of insertion. The attacker first submits a crafted value through the configuration interface, which writes the payload into persistent storage. Later, an unrelated code path retrieves the stored value and concatenates it directly into a SQL statement. Because the retrieval path assumes stored data is trusted, no escaping or prepared statement binding is performed before execution.

This class of flaw is harder to detect through black-box scanning because the injection point and the execution point are decoupled. Exploitation requires authentication and permission to modify the currency_symbol field, which limits the attack surface to users who already have configuration access. Once triggered, the injected SQL runs with the database privileges of the application service account.

Root Cause

The root cause is a failure to apply parameterized queries or input sanitization when the currency_symbol value is reused in dynamic SQL construction. The developer trust boundary between stored configuration data and runtime query construction was not enforced, allowing tainted data to flow into the SQL execution context.

Attack Vector

An attacker with valid credentials and access to the configuration interface submits a payload such as a SQL fragment into the currency_symbol field. The payload is stored in the database. When the application subsequently builds a query that includes this value through string concatenation, the injected SQL executes. The attacker can extract data, modify records, or perform database-level reconnaissance depending on the underlying DBMS and account privileges. See the CVE-2026-26745 research write-up for proof of concept details.

Detection Methods for CVE-2026-26745

Indicators of Compromise

• Unusual SQL syntax characters such as single quotes, comment markers, or UNION keywords stored in the currency_symbol configuration field
• Database error log entries referencing malformed queries that include currency configuration values
• Unexpected outbound database queries executed during routine page loads that reference configuration tables

Detection Strategies

• Review configuration table contents for non-printable or SQL-meaningful characters in currency_symbol and adjacent fields
• Enable database query logging and search for concatenated query patterns that include configuration-derived values
• Audit application logs for configuration changes correlated with subsequent anomalous query behavior

Monitoring Recommendations

• Monitor administrative account activity that modifies POS configuration settings
• Alert on database errors originating from query paths that reference configuration data
• Track outbound data volumes from the POS database to identify potential exfiltration via injected queries

How to Mitigate CVE-2026-26745

Immediate Actions Required

• Restrict access to the OpenSourcePOS configuration interface to a minimal set of trusted administrators
• Inspect the current value of the currency_symbol field and reset it to a known-good string
• Apply the principle of least privilege to the database account used by the OpenSourcePOS application

Patch Information

At the time of publication, no fixed version is referenced in the NVD entry for OpenSourcePOS 3.4.1. Monitor the OpenSourcePOS GitHub repository for upstream patches that introduce parameterized queries or input validation for the currency_symbol field.

Workarounds

• Apply a custom patch to convert the affected query to use prepared statements with bound parameters
• Add server-side validation that rejects non-alphanumeric or non-currency characters in the currency_symbol field before storage
• Place the application behind a web application firewall configured to inspect configuration update requests for SQL metacharacters
• Revoke unnecessary database privileges such as DROP, ALTER, or access to sensitive tables from the application's database user