Vulnerability · Published Apr 21, 2026 · Assigned by GitHub_M
CVE-2026-40871mailcow: dockerized vulnerable to Second Order SQL Injection in quarantine category via API
High 7.2
In plain English
A high-severity improper input validation in mailcow-dockerized from mailcow. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 8.6% (higher than 95% of all known vulnerabilities).
Official description
mailcow: dockerized is an open source groupware/email suite based on docker. Versions prior to 2026-03b have a second-order SQL injection vulnerability in the quarantine_category field via the Mailcow API. The /api/v1/add/mailbox endpoint stores quarantine_category without validation or sanitization. This value is later used by quarantine_notify.py, which constructs SQL queries using unsafe % string formatting instead of parameterized queries. This results in a delayed (second-order) SQL injection when the quarantine notification job executes, allowing an attacker to inject arbitrary SQL. Using a UNION SELECT, sensitive data (e.g., admin credentials) can be exfiltrated and rendered inside quarantine notification emails. Version 2026-03b fixes the vulnerability.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| mailcow | mailcow-dockerized | < 2026-03b |
Weakness: CWE-20, CWE-89, CWE-116, CWE-564 · Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H