CVE-2023-42809
CRITICALRedisson unsafe deserialization vulnerability
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
org.redisson:redissonReal-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
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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | org.redisson:redisson | all versions | 3.22.0 |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.redisson:redisson. 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.redisson:redisson to 3.22.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-42809 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-2023-42809 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-2023-42809. 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-2023-42809 in your dependencies?
O3 detects CVE-2023-42809 across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.