Trigger.dev: Prototype pollution via run metadata operations → process-wide cross-tenant DoS

Trigger.dev is a platform for building and deploying fully managed AI agents and workflows. From 3.3.8 until 4.5.6, the PUT /api/v1/runs/:runId/metadata endpoint passes attacker-controlled operation.key values to new JSONHeroPath(operation.key).set(newMetadata, value) in packages/core/src/v3/runMetadata/operations.ts without rejecting dangerous constructor and prototype path segments. A caller with a normal environment API key can pollute Object.prototype in the shared webapp process, corrupting Prisma queries and Prometheus labels, breaking other tenants' worker authentication, and causing a process-wide denial of service. This issue is fixed in version 4.5.6.