SQL Injection in Mailcow Mailcow-Dockerized

CVE-2026-40871

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.

Vulnerability class: Drupalgeddon 2 (CVE-2018-7600)

Published · last modified .

CVSS v3 metric

CVSS v3 base score 7.2 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.004 (37.9th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 38th percentile — 37.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-40871: fell from 0.093 to 0.004.

EPSS over last 30 days · oldest: 0.093 · newest: 0.004 · change: -0.089

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-40871?
CVE-2026-40871 is a high-severity vulnerability in Mailcow Mailcow-Dockerized, classified under Improper Input Validation. CVSS score: 7.2/10. Published 2026-04-21.
How severe is CVE-2026-40871?
High severity. CVSS v3 base score is 7.2 out of 10.