THREATPORT/VULNERABILITY/CVE-2026-40871
HIGH SEVERITY

CVE-2026-40871

CVE-2026-40871 vulnerability

CVSS
7.2
EPSS
9.9%
EPSS pct
95th
Exploited
No known
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 vendor
See references
Affected product
See references
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
Weakness type (CWE)
Published
2026-04-21

Risk analysis

Based on its CVSS vector, this vulnerability is exploitable over the network, low attack complexity, requiring high privileges, no user interaction. Successful exploitation leads to high impact to confidentiality, high impact to integrity, high impact to availability.

Its EPSS score of 9.9% reflects a lower probability of exploitation activity in the wild over the next 30 days, placing it above 95% of all scored CVEs.

Check your external exposure to CVE-2026-40871

  • Confirm whether the affected software is running on any internet-facing host or subdomain.
  • Match discovered service fingerprints against the version affected by CVE-2026-40871.
  • Prioritise remediation if the asset is public, business-critical, or near authentication/payment flows.

How ThreatPort helps with CVE-2026-40871

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