CVE-2026-48188: OTRS Auth Bypass Vulnerability

CVE-2026-48188 Overview

CVE-2026-48188 is an unauthenticated SQL injection vulnerability in the database layer module of OTRS and ((OTRS)) Community Edition. The flaw stems from improper input validation [CWE-20] and allows attackers to bypass authentication entirely. Exploitation requires the backend MySQL or MariaDB server to be configured with the NO_BACKSLASH_ESCAPES SQL mode. When this condition is met, an unauthenticated remote attacker can inject SQL via the network with no user interaction.

Critical Impact

Unauthenticated attackers can bypass authentication on internet-facing OTRS instances, gaining access to ticketing data, customer records, and administrative functionality.

Affected Products

• OTRS versions 7.0.X, 8.0.X, 2023.X, 2024.X, 2025.X, and 2026.X before 2026.4.X
• ((OTRS)) Community Edition 6.0.x
• Third-party products derived from ((OTRS)) Community Edition

Discovery Timeline

• 2026-06-01 - CVE-2026-48188 published to NVD
• 2026-06-01 - Last updated in NVD database

Technical Details for CVE-2026-48188

Vulnerability Analysis

The vulnerability resides in the OTRS database abstraction layer, which fails to properly sanitize user-supplied input before incorporating it into SQL statements. OTRS escapes single quotes by prefixing them with a backslash, a strategy that depends on the database engine interpreting backslashes as escape characters. When MySQL or MariaDB runs with NO_BACKSLASH_ESCAPES enabled, backslashes are treated as literal characters. The escape logic breaks, and attacker-controlled quotes terminate string literals inside generated queries.

The attack surface includes pre-authentication endpoints reachable by any network client. Because the injection occurs before authentication completes, an attacker can manipulate identity checks and impersonate any user, including administrators.

Root Cause

The root cause is reliance on backslash escaping without verifying the active SQL mode on the database server. The application assumes default MySQL behavior and does not use parameterized queries or context-aware encoding. Input validation is insufficient to neutralize quote characters when NO_BACKSLASH_ESCAPES is set.

Attack Vector

Attackers send crafted HTTP requests containing single-quote payloads to unauthenticated OTRS endpoints. The malformed escape produces a syntactically valid but attacker-controlled SQL statement. The resulting query manipulation enables authentication bypass and data extraction. No credentials or user interaction are required.

Details are documented in the OTRS Security Advisory 2026-02.

Detection Methods for CVE-2026-48188

Indicators of Compromise

• Unexpected successful logins to OTRS administrative accounts without preceding failed authentication attempts.
• HTTP request bodies or query strings containing unescaped single quotes targeting OTRS login or customer interface endpoints.
• Database logs showing malformed or unusually structured SQL statements originating from the OTRS application user.
• New agent or customer accounts created outside of normal change-management windows.

Detection Strategies

• Inspect OTRS web server access logs for requests containing ', --, UNION, or OR 1=1 patterns directed at index.pl or customer.pl.
• Audit the MySQL or MariaDB configuration with SELECT @@sql_mode; to identify instances running with NO_BACKSLASH_ESCAPES, which mark exploitable hosts.
• Correlate authentication events with source IP reputation to surface successful logins from previously unseen addresses.

Monitoring Recommendations

• Enable MySQL general query logging on OTRS database hosts and forward to a centralized log platform for retroactive analysis.
• Alert on SQL syntax errors emitted by the OTRS application logs, which often accompany injection attempts.
• Monitor for privilege changes within the users and groups tables in the OTRS schema.

How to Mitigate CVE-2026-48188

Immediate Actions Required

• Upgrade OTRS to version 2026.4.X or later as published in OTRS Security Advisory 2026-02.
• Verify the SQL mode on every MySQL or MariaDB instance backing OTRS and remove NO_BACKSLASH_ESCAPES until patching completes.
• Restrict network exposure of the OTRS web interface to trusted networks or place it behind a VPN.
• Rotate credentials and API tokens for any OTRS instance that was internet-reachable while running NO_BACKSLASH_ESCAPES.

Patch Information

OTRS Group released fixed builds in the 2026.4.X branch. Customers on legacy versions (7.0.X, 8.0.X, 2023.X, 2024.X, 2025.X) and ((OTRS)) Community Edition 6.0.x should consult the OTRS Security Advisory 2026-02 for upgrade guidance. Community Edition forks may require manual backporting of the database layer fix.

Workarounds

• Remove NO_BACKSLASH_ESCAPES from the sql_mode directive in my.cnf and restart the database service to eliminate the precondition.
• Place a web application firewall in front of OTRS with rules blocking SQL injection patterns on pre-authentication endpoints.
• Disable external customer interface access if it is not required for business operations.

# Verify and correct the MySQL/MariaDB SQL mode
mysql -u root -p -e "SELECT @@GLOBAL.sql_mode;"

# In /etc/mysql/my.cnf under [mysqld], ensure NO_BACKSLASH_ESCAPES is absent:
# sql_mode = "STRICT_TRANS_TABLES,NO_ENGINE_SUBSTITUTION"

systemctl restart mariadb