CVE intelligence and bounded remediation

CVE-2023-42809 — Redisson is a Java Redis client that uses the Netty framework

Critical CVSS 9.6

Redisson is a Java Redis client that uses the Netty framework. Prior to version 3.22.0, some of the messages received from the Redis server contain Java objects that the client deserializes without further validation. Attackers that manage to trick clients into communicating with a malicious server can include especially crafted objects in its responses that, once deserialized by the client, force it to execute arbitrary code. This can be abused to take control of the machine the client is running in. Version 3.22.0 contains a patch for this issue. Some post-fix advice is available. Do NOT use `Kryo5Codec` as deserialization codec, as it is still vulnerable to arbitrary object deserialization due to the `setRegistrationRequired(false)` call. On the contrary, `KryoCodec` is safe to use. The fix applied to `SerializationCodec` only consists of adding an optional allowlist of class names, even though making this behavior the default is recommended. When instantiating `SerializationCodec` please use the `SerializationCodec(ClassLoader classLoader, Set<String> allowedClasses)` constructor to restrict the allowed classes for deserialization.

Severity
Critical
CVSS
9.6 (3.1)
Published
2023-10-04
CISA KEV
Not currently listed
Ecosystem
java/maven
Weaknesses
CWE-502

Affected products

  • redisson / redisson

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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