CVE-2025-55039
MEDIUMCVE-2025-55039 is a medium-severity (CVSS 6.5) CWE-326 vulnerability in org.apache.spark:spark-network-common_2.13. O3 Security confirms whether CVE-2025-55039 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Apache Spark, Apache Spark: RPC encryption defaults to unauthenticated AES-CTR mode, enabling man-in-the-middle ciphertext modification attacks
Blast Radius
org.apache.spark:spark-network-common_2.13☕org.apache.spark:spark-network-common_2.13☕org.apache.spark:spark-network-common_2.12☕org.apache.spark:spark-network-common_2.12🐍pyspark🐍pysparkReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
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 Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | org.apache.spark:spark-network-common_2.13 | ≥ 3.5.0&&< 3.5.2 | 3.5.2 |
| ☕Maven | org.apache.spark:spark-network-common_2.13 | all versions | 3.4.4 |
| ☕Maven | org.apache.spark:spark-network-common_2.12 | all versions | 3.4.4 |
| ☕Maven | org.apache.spark:spark-network-common_2.12 | ≥ 3.5.0&&< 3.5.2 | 3.5.2 |
| 🐍PyPI | pyspark | all versions | 3.4.4 |
| 🐍PyPI | pyspark | ≥ 3.5.0&&< 3.5.2 | 3.5.2 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.apache.spark:spark-network-common_2.13. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update org.apache.spark:spark-network-common_2.13 to 3.5.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-55039 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2025-55039 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2025-55039. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2025-55039 in your dependencies?
O3 detects CVE-2025-55039 across Maven, PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.