9.8

CVSS Score

3.1

-

CVSS Score

Basic Information

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CVE-2017-20189

CVE-2017-20189: Clojure classes can be used to craft a serialized object that runs arbitrary code on deserialization

In Clojure before 1.9.0, classes can be used to construct a serialized object that executes arbitrary code upon deserialization. This is relevant if a server deserializes untrusted objects.

(GitHub Advisory)

Miggo Vulnerability Database

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CVE-2017-20189

CVE-2017-20189:

9.8

CVSS Score

3.1

-

CVSS Score

Basic Information

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Technical Details

Package Name	Ecosystem	Vulnerable Versions	First Patched Version
org.clojure:clojure	maven	< 1.9.0	1.9.0

Technical Details

Vulnerability Intelligence
Miggo AI

Root Cause Analysis

The vulnerability stems from Clojure's proxy class generation mechanism. The generate-proxy function created serializable proxy classes (when extending Serializable interfaces) that stored method implementations in __clojureFnMap. Attackers could craft objects with malicious function mappings that execute during deserialization via HashMap deserialization triggers. The patch explicitly disabled serialization by adding writeObject/readObject methods that throw NotSerializableException, confirming this as the root cause. The test cases added in java_interop.clj specifically validate the proxy serialization prohibition, further reinforcing this as the vulnerable code path.

Vulnerable functions

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WAF Protection Rules

WAF Rule

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Reasoning

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