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Werk #18300: Rulesets: Accept valid regex patterns in explicit host conditions

Component Setup
Title Rulesets: Accept valid regex patterns in explicit host conditions
Date Apr 17, 2026
Level Trivial Change
Class Bug Fix
Compatibility Compatible - no manual interaction needed
Checkmk versions & editions
2.6.0b1
Not yet released
Checkmk Community, Checkmk Pro, Checkmk Ultimate, Checkmk Cloud, Checkmk Ultimate MT
2.5.0b5
Not yet released
Checkmk Community, Checkmk Pro, Checkmk Ultimate, Checkmk Cloud, Checkmk Ultimate MT
2.4.0p27
Not yet released
Checkmk Community, Checkmk Pro, Checkmk Ultimate, Checkmk Cloud, Checkmk Ultimate MT
2.3.0p47
Not yet released
Checkmk Community, Checkmk Pro, Checkmk Ultimate, Checkmk Ultimate MT

Werk #18988 introduced validation of regex patterns in explicit host conditions. However, valid regex patterns starting with ~ were afterwards incorrectly rejected as invalid hostnames: after a successful regex compile, the code fell through to hostname validation, which rightfully refused the regex as a host name.

Valid regex patterns are now accepted again. Invalid ones still produce a clear error message, as intended by werk #18988.

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