CVE-2025-55039

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

MEDIUM

6.5

CVSS Score

Published: October 15, 2025 at 07:19 AM UTC

Updated: October 8, 2026 at 12:10 PM UTC

1 product affected across 1 vendorSpark

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Severity

MEDIUM6.5

Exploit prediction

EPSS 0.2%

SSVC

No known exploit

Description

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Spark · Apachemaven

95%

v < 3.4.40 ≤ v < 3.4.43.5.0 ≤ v < 3.5.2*03.5.0

Affected range stops below 3.4.4, so it looks safe — our inference, not a vendor statement

Affected range stops below 3.5.2, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

https://lists.apache.org/thread/zrgyy9l85nm2c7vk36vr7bkyorg3w4qq

References (2)

Vendor AdvisoryMailing List

Source: cverecord

https://lists.apache.org/thread/zrgyy9l85nm2c7vk36vr7bkyorg3w4qq

Source: af854a3a-2127-422b-91ae-364da2661108

http://www.openwall.com/lists/oss-security/2025/10/14/11

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

6.5MEDIUMCISA-ADP

Attack Vector: NETWORK
Complexity: LOW
Privileges: NONE
User Interaction: NONE
Scope: UNCHANGED
Confidentiality: LOW
Integrity: LOW
Availability: NONE

Vector?

Quick Info

StatusMODIFIED

CWE

CWE-347CWE-326

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