SpEL Injection in `PUT /api/v1/events/subscriptions` 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. Similarly to the GHSL-2023-250 issue, AlertUtil::validateExpression is also called from EventSubscriptionRepository.prepare(), which can lead to Remote Code Execution. prepare() is called from EntityRepository.prepareInternal() which, in turn, gets called from EntityResource.createOrUpdate(). Note that, even though there is an authorization check (authorizer.authorize()), it gets called after prepareInternal() gets called and, therefore, after the SpEL expression has been evaluated. In order to reach this method, an attacker can send a PUT request to /api/v1/events/subscriptions which gets handled by EventSubscriptionResource.createOrUpdateEventSubscription(). This vulnerability was discovered with the help of CodeQL's Expression language injection (Spring) query. 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. This issue is also tracked as GHSL-2023-251.