CVE intelligence and bounded remediation

CVE-2023-34108 — Mailcow Mailcow: Dockerized security vulnerability

High CVSS 8.8

mailcow is a mail server suite based on Dovecot, Postfix and other open source software, that provides a modern web UI for user/server administration. A vulnerability has been discovered in mailcow which allows an attacker to manipulate internal Dovecot variables by using specially crafted passwords during the authentication process. The issue arises from the behavior of the `passwd-verify.lua` script, which is responsible for verifying user passwords during login attempts. Upon a successful login, the script returns a response in the format of "password=<valid-password>", indicating the successful authentication. By crafting a password with additional key-value pairs appended to it, an attacker can manipulate the returned string and influence the internal behavior of Dovecot. For example, using the password "123 mail_crypt_save_version=0" would cause the `passwd-verify.lua` script to return the string "password=123 mail_crypt_save_version=0". Consequently, Dovecot will interpret this string and set the internal variables accordingly, leading to unintended consequences. This vulnerability can be exploited by an authenticated attacker who has the ability to set their own password.…

Severity
High
CVSS
8.8 (3.1)
Published
2023-06-07
CISA KEV
Not currently listed
Ecosystem
software/application
Weaknesses
CWE-78

Affected products

  • mailcow / mailcow:_dockerized

Matched remediation archetype

Command, code, expression, and template injection

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Check exposure

  • Trace untrusted values to process execution, interpreters, evaluators, template engines, dynamic imports, and administrative scripting features.
  • Determine whether the affected path is reachable across each trust boundary and which service account or host privilege it inherits.
  • Review configuration for optional execution features, unsafe compatibility modes, and shell invocation.

Remediate safely

  • Replace string-built commands or evaluated code with fixed operations and structured argument APIs that do not invoke a shell.
  • Use strict allowlists for operation identifiers and reject unexpected input before it reaches any interpreter.
  • Update the affected component and add inert regression tests covering metacharacters, encoding variants, and alternate request paths.

Authoritative sources

Complete CVE record and remediation plan

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