CVE intelligence and bounded remediation

CVE-2017-3203 — Pivotal Spring-Flex security vulnerability

High CVSS 8.1

The Java implementations of AMF3 deserializers in Pivotal/Spring Spring-flex derive class instances from java.io.Externalizable rather than the AMF3 specification's recommendation of flash.utils.IExternalizable. A remote attacker with the ability to spoof or control an RMI server connection may be able to send serialized Java objects that execute arbitrary code when deserialized.

Severity
High
CVSS
8.1 (3.0)
Published
2018-06-11
CISA KEV
Not currently listed
Ecosystem
java/maven
Weaknesses
CWE-502

Affected products

  • pivotal / spring-flex

Matched remediation archetype

Unsafe deserialization and object reconstruction

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Check exposure

  • Inventory serialization formats accepted from requests, queues, caches, files, cookies, and cross-service messages.
  • Trace whether untrusted input can select classes, types, callbacks, constructors, or object hooks during decoding.
  • Identify signing, schema validation, trust-boundary, and compatibility settings for each decoder.

Remediate safely

  • Replace native object deserialization with a data-only format and explicit schema validation.
  • If replacement is not immediate, use a safe decoder with a minimal type allowlist and disable polymorphic or executable hooks.
  • Update the affected library and add inert tests for unknown types, extra fields, malformed nesting, and unsigned data.

Authoritative sources

Complete CVE record and remediation plan

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