CVE-2026-40871Public exploitNetwork attack vector

Arbitrary SQL execution via unsafe quarantine query formatting

Published Apr 21, 2026 · Updated Apr 21, 2026

Second-order SQL injection in mailcow: dockerized before 2026-03b allows remote authenticated users to execute arbitrary SQL via its API. The add-mailbox endpoint stores quarantine_category without validation, and quarantine_notify.py later inserts it into SQL through percent-string formatting. Exploitation requires privileged API access and a subsequent quarantine event; query results can expose administrator credentials in notification emails.

CVSS severity7.2
High
EPSS probability9.33%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Second-order SQL injection in mailcow: dockerized before 2026-03b allows remote authenticated users to execute arbitrary SQL via its API. The add-mailbox endpoint stores quarantine_category without validation, and quarantine_notify.py later inserts it into SQL through percent-string formatting. Exploitation requires privileged API access and a subsequent quarantine event; query results can expose administrator credentials in notification emails.

The record

CVE
CVE-2026-40871
Published
Apr 21, 2026
Updated
Apr 21, 2026
Vendor
mailcow
Product
mailcow: dockerized
Classifications
CWE-564, CWE-89, CWE-20, CWE-116, T1190
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 21, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 21, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 2026-03b

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

mailcow · mailcow: dockerizedversion=< 2026-03b

Published CVSS scores

7.2GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-564SQL Injection: Hibernate
CWE-89Improper Neutralization of Special Elements used in an SQL Command ('SQL Injection')
CWE-20Improper Input Validation
CWE-116Improper Encoding or Escaping of Output
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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