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Improper Neutralization of Special Elements Used in a Template Engine

CVE-2025-53909

High
9.1/10

Summary

mailcow: dockerized is an open source groupware/email suite based on docker. A Server-Side Template Injection (SSTI) vulnerability exists in versions prior to 2025-07 in the notification template system used by mailcow for sending quota and quarantine alerts. The template rendering engine allows template expressions that may be abused to execute code in certain contexts. The issue requires admin-level access to mailcow UI to configure templates, which are automatically rendered during normal system operation. Version 2025-07 contains a patch for the issue.

  • LOW
  • NETWORK
  • HIGH
  • CHANGED
  • NONE
  • HIGH
  • HIGH
  • HIGH

CWE-1336 - Improper Neutralization of Special Elements Used in a Template Engine

The product uses a template engine to insert or process externally-influenced input, but it does not neutralize or incorrectly neutralizes special elements or syntax that can be interpreted as template expressions or other code directives when processed by the engine.

References

Advisory Timeline

  • Published