CVE-2026-4776: Mautic API SQL Injection Vulnerability

CVE-2026-4776 Overview

CVE-2026-4776 is a SQL injection vulnerability in Mautic's API contact filtering mechanism. The flaw exists because the application fails to recursively sanitize nested query parameters submitted to the contact filtering endpoints. An authenticated API user can craft nested filter payloads that bypass input validation and inject arbitrary SQL statements into the underlying database query.

The vulnerability is tracked under CWE-89: Improper Neutralization of Special Elements used in an SQL Command. Mautic disclosed the issue through a GitHub Security Advisory.

Critical Impact
Authenticated attackers can extract sensitive data from the Mautic database, including marketing contact records, credentials, and configuration tables, by injecting SQL through nested API filter parameters.

Affected Products

Mautic marketing automation platform
Mautic REST API contact endpoints
Deployments exposing the API to authenticated users with contact read permissions

Discovery Timeline

2026-05-29 - CVE-2026-4776 published to the National Vulnerability Database
2026-05-29 - Last updated in NVD database

Technical Details for CVE-2026-4776

Vulnerability Analysis

The vulnerability resides in Mautic's contact filtering logic exposed through the REST API. Mautic accepts nested query parameters that allow API consumers to construct compound filter expressions against the contact data model. The sanitization routine that processes these filters operates at the top level of the parameter array but does not descend recursively into nested arrays or objects.

When an attacker submits a filter payload containing nested structures, untrusted values reach the query builder unsanitized. The unsanitized fragments are concatenated into the SQL statement executed against the backing database. This permits classic SQL injection techniques, including UNION-based extraction, boolean-based blind injection, and time-based blind injection. Confidentiality impact is high because the contact database typically stores personal data, authentication artifacts, and integration secrets.

Root Cause

The root cause is incomplete input validation [CWE-89]. The filter sanitizer does not traverse nested parameter structures. Attackers place malicious SQL fragments deeper in the parameter tree to evade the shallow validation pass before the input reaches the query builder.

Attack Vector

Exploitation requires network access to the Mautic API and valid credentials with permission to query contacts. The attacker issues a crafted HTTP request to a contact filtering endpoint with nested where or filter parameters. The injected SQL executes with the privileges of the Mautic database user. No user interaction is required. Refer to the Mautic Security Advisory GHSA-fcmw-wx57-9p75 for technical specifics.

Detection Methods for CVE-2026-4776

Indicators of Compromise

API requests to Mautic contact endpoints containing SQL keywords such as UNION, SELECT, SLEEP(, or INFORMATION_SCHEMA inside nested filter or where parameters.
Database query logs showing malformed or unexpectedly long SQL statements originating from the Mautic application user.
Anomalous spikes in API response times tied to a single authenticated account, suggesting time-based blind injection.
Unexpected outbound data transfers correlated with authenticated API sessions accessing /api/contacts.

Detection Strategies

Inspect web server and application logs for nested query string parameters containing SQL metacharacters such as single quotes, parentheses, or comment sequences (--, /*).
Enable database query logging on the Mautic backend and alert on queries that reference system tables or contain stacked statements.
Deploy a Web Application Firewall (WAF) ruleset that decodes nested parameter structures before applying SQL injection signatures.

Monitoring Recommendations

Baseline normal API consumer behavior and alert on accounts that suddenly generate large filter payloads or unusual query volume.
Forward Mautic application logs and database audit logs to a centralized SIEM for correlation against authentication events.
Monitor for privilege changes or new API tokens issued shortly before suspicious filter activity.

How to Mitigate CVE-2026-4776

Immediate Actions Required

Upgrade Mautic to the patched release identified in GHSA-fcmw-wx57-9p75 as soon as it is available in your environment.
Audit all API tokens and revoke credentials that are not actively used or that belong to inactive integrations.
Review database audit logs for evidence of prior exploitation before applying the patch.

Patch Information

Mautic published the fix through the GitHub Security Advisory GHSA-fcmw-wx57-9p75. The patched release replaces the shallow filter sanitizer with a recursive sanitization routine that validates every leaf value in nested parameter structures before query construction.

Workarounds

Restrict API access to trusted network ranges using firewall or reverse-proxy ACLs until the patch is applied.
Apply WAF rules that reject API requests containing nested filter parameters with SQL metacharacters.
Reduce permissions of the Mautic database user to the minimum required, removing rights such as FILE, CREATE, and access to unrelated schemas.
Disable or limit API contact filtering endpoints for low-trust user roles where business requirements allow.

bash

# Example: restrict Mautic API access at the reverse proxy (nginx)
location /api/ {
    allow 10.0.0.0/8;
    deny  all;
    proxy_pass http://mautic_backend;
}