SpEL Injection in `GET /api/v1/events/subscriptions/validation/condition/<expr>` in OpenMetadata

OpenMetadata is a unified platform for discovery, observability, and governance powered by a central metadata repository, in-depth lineage, and seamless team collaboration. The `‎AlertUtil::validateExpression` method evaluates an SpEL expression using `getValue` which by default uses the `StandardEvaluationContext`, allowing the expression to reach and interact with Java classes such as `java.lang.Runtime`, leading to Remote Code Execution. The `/api/v1/events/subscriptions/validation/condition/<expression>` endpoint passes user-controlled data `AlertUtil::validateExpession` allowing authenticated (non-admin) users to execute arbitrary system commands on the underlaying operating system. In addition, there is a missing authorization check since `Authorizer.authorize()` is never called in the affected path and, therefore, any authenticated non-admin user is able to trigger this endpoint and evaluate arbitrary SpEL expressions leading to arbitrary command execution. This vulnerability was discovered with the help of CodeQL's Expression language injection (Spring) query and is also tracked as `GHSL-2023-235`. This issue may lead to Remote Code Execution and has been addressed in version 1.2.4. Users are advised to upgrade. There are no known workarounds for this vulnerability.