Apache Spark, Apache Spark: RPC encryption defaults to unauthenticated AES-CTR mode, enabling man-in-the-middle ciphertext modification attacks

Summary

This issue affects Apache Spark versions before 3.4.4, 3.5.2 and 4.0.0. Apache Spark versions before 4.0.0, 3.5.2 and 3.4.4 use an insecure default network encryption cipher for RPC communication between nodes. When spark.network.crypto.enabled is set to true (it is set to false by default), but spark.network.crypto.cipher is not explicitly configured, Spark defaults to AES in CTR mode (AES/CTR/NoPadding), which provides encryption without authentication. This vulnerability allows a man-in-the-middle attacker to modify encrypted RPC traffic undetected by flipping bits in ciphertext, potentially compromising heartbeat messages or application data and affecting the integrity of Spark workflows. To mitigate this issue, users should either configure spark.network.crypto.cipher to AES/GCM/NoPadding to enable authenticated encryption or enable SSL encryption by setting spark.ssl.enabled to true, which provides stronger transport security.

Timeline

1. Oct 15, 2025, 7:19 AM UTCCVE published
2. Oct 15, 2025, 7:33 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: no · Technical impact: partial

3. Nov 4, 2025, 9:13 PM UTCRecord last updated

Affected versions

• org.apache.spark:spark-network-common_2.13

  From 3.5.0 · fixed in 3.5.2; fixed in 3.4.4

• org.apache.spark:spark-network-common_2.12

  From 3.5.0 · fixed in 3.5.2; fixed in 3.4.4

• pysparkPyPI

  fixed in 3.4.4; From 3.5.0 · fixed in 3.5.2

• org.apache.spark:spark-network-common_2.13Maven

  From 3.5.0 · fixed in 3.5.2

• org.apache.spark:spark-network-common_2.13Maven

  fixed in 3.4.4

• org.apache.spark:spark-network-common_2.12Maven

  fixed in 3.4.4

• org.apache.spark:spark-network-common_2.12Maven

  From 3.5.0 · fixed in 3.5.2

• pysparkPyPI

  fixed in 3.4.4

• pysparkPyPI

  From 3.5.0 · fixed in 3.5.2

References 1