Sentry is an error tracking and performance monitoring platform. Starting in version 23.6.0 and prior to version 23.6.2, the Sentry API incorrectly returns the "access-control-allow-credentials: true" HTTP header if the "Origin" request header ends with the "system.base-hostname" option of Sentry installation. This only affects installations that have "system.base-hostname" option explicitly set, as it is empty by default. Impact is limited since recent versions of major browsers have cross-site cookie blocking enabled by default. However, this flaw could allow other multi-step attacks. The patch has been released in Sentry 23.6.2.