Tandoor Recipes: ReDoS (Regular Expression Denial of Service) via User-Controlled Automation Regex Patterns

Tandoor Recipes is an application for managing recipes, planning meals, and building shopping lists. Prior to 2.6.10, executes user-controlled Automation regular-expression patterns with Python re.sub() without complexity validation or an execution timeout when an authenticated user stores a catastrophic-backtracking regex and any user in the same Space imports a matching recipe. Request processing uses Automation.param_2, apply_regex_replace_automation, sub, api/recipe-from-source/. The attack works because the shared-Space automation engine evaluates the malicious pattern during recipe import and can occupy a Gunicorn worker until its request timeout. This can exhaust application worker slots and make the service unavailable to users. This issue is fixed in version 2.6.10.