CVE intelligence and bounded remediation

CVE-2023-26490 — mailcow is a dockerized email package, with multiple containers linked in one bridged network

High CVSS 8.8

mailcow is a dockerized email package, with multiple containers linked in one bridged network. The Sync Job feature - which can be made available to standard users by assigning them the necessary permission - suffers from a shell command injection. A malicious user can abuse this vulnerability to obtain shell access to the Docker container running dovecot. The imapsync Perl script implements all the necessary functionality for this feature, including the XOAUTH2 authentication mechanism. This code path creates a shell command to call openssl. However, since different parts of the specified user password are included without any validation, one can simply execute additional shell commands. Notably, the default ACL for a newly-created mailcow account does not include the necessary permission. The Issue has been fixed within the 2023-03 Update (March 3rd 2023). As a temporary workaround the Syncjob ACL can be removed from all mailbox users, preventing from creating or changing existing Syncjobs.

Severity
High
CVSS
8.8 (3.1)
Published
2023-03-04
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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