Airflow: reserved serialization keys in Dag run conf crash the scheduler or build objects in the Triggerer

Impact

Airflow does not reject reserved serialization keys inside a Dag run's conf. When a Dag uses a deadline alert with an asynchronous callback and the deadline is missed, a crafted conf either crashes the scheduler over and over or is rebuilt into objects inside the Triggerer. A scheduler in a crash loop stops every pipeline it runs, not only the attacker's. The record does not say what object construction in the Triggerer can lead to.

Who can reach it

An authenticated user allowed to trigger a Dag that uses a deadline alert with an asynchronous callback.

What to do

Upgrade apache-airflow to 3.4.0 or later and restart the scheduler and Triggerer.

References

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