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.
Fix
Patch, vendor advisory and mitigation references on NVD 1
- https://lists.apache.org/thread/zrgyy9l85nm2c7vk36vr7bkyorg3w4qq Mailing List, Vendor Advisory
Every line above is quoted from NVD, CISA, Microsoft, the vendor's own advisory or DISA; nothing is generated.
Change history 1
- First seenCVSS 6.5 · apacheNVD modified 2026-10-08 12:10
Affected (CPE criteria) 1
cpe:2.3:a:apache:spark:*:*:*:*:*:*:*:*
References 2
- https://lists.apache.org/thread/zrgyy9l85nm2c7vk36vr7bkyorg3w4qq Mailing List, Vendor Advisory
- http://www.openwall.com/lists/oss-security/2025/10/14/11