CVE-2025-53909Network attack vector

Administrator code execution via unsandboxed notification templates

Published Jul 17, 2025 · Updated Jul 17, 2025

Server-side template injection in mailcow: dockerized before 2025-07 allows remote authenticated users to execute code through alert templates. The quota_notify.py and quarantine_notify.py paths render administrator-controlled QW_HTML and Q_HTML strings with unrestricted Jinja2 Template objects. An administrator must save a malicious quota or quarantine template; routine notification rendering then executes it in the Dovecot container.

CVSS severity9.1
Critical
EPSS probability0.46%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Server-side template injection in mailcow: dockerized before 2025-07 allows remote authenticated users to execute code through alert templates. The quota_notify.py and quarantine_notify.py paths render administrator-controlled QW_HTML and Q_HTML strings with unrestricted Jinja2 Template objects. An administrator must save a malicious quota or quarantine template; routine notification rendering then executes it in the Dovecot container.

The record

CVE
CVE-2025-53909
Published
Jul 17, 2025
Updated
Jul 17, 2025
Vendor
mailcow
Product
mailcow: dockerized
Classifications
T1059.006
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. Jul 17, 2025CVE publishedPublication date reported by the CVE source.
  2. Jul 17, 2025Record 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=< 2025-07

What conditions does exploitation require?

Attack vectornetwork
Required privilegesadmin

What is affected?

mailcow · mailcow: dockerizedversion=< 2025-07

Published CVSS scores

9.1GitHubCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/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
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1059.006Python

Public exploit references

No public exploit references are available in this record.

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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