CVE-2026-40871 mailcow: dockerized vulnerable to Second Order SQL Injection in quarantine category via API
Attackers can inject SQL via the API to exfiltrate sensitive data like admin credentials through delayed quarantine notifications.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-40871?
CVE-2026-40871 is a high-severity SQL injection vulnerability in mailcow-dockerized, published on 21 Apr 2026. An attacker needs administrator access to exploit it, with no action from the victim.
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.
Which versions are affected by CVE-2026-40871?
How do I fix CVE-2026-40871?
No fix has been published for CVE-2026-40871 yet. Limit exposure of the affected software until one is available.
Use parameterised queries everywhere and never build SQL by joining strings. Upgrade affected software first; a web application firewall only buys time. More about SQL injection.
Is CVE-2026-40871 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-40871 exists.
Sources
Also known as GHSA-r8fq-wrfm-cj2q.