Trigger.dev's PUT /api/v1/runs/:runId/metadata endpoint improperly handles attacker-controlled operation.key values by passing them to new JSONHeroPath(operation.key).set(newMetadata, value) without rejecting dangerous constructor and prototype path segments. This allows an attacker to perform prototype pollution on Object.prototype within the shared webapp process. The pollution can corrupt Prisma queries and Prometheus labels, disrupt other tenants' worker authentication, and cause a denial of service affecting the entire process. The vulnerability affects versions prior to 4.5.6 and is fixed in 4.5.6.

An attacker with a normal environment API key can exploit this vulnerability to modify the Object.prototype, which leads to corruption of database queries and monitoring labels, breaks authentication for other tenants sharing the service, and causes a denial of service that affects the entire process. This results in significant service disruption and potential multi-tenant impact.

A fix is available in Trigger.dev version 4.5.6. Users should upgrade to version 4.5.6 or later to remediate this vulnerability. No other mitigation guidance is provided or required.