GHSA-crg9-44h2-xw35 is a critical-severity (CVSS 10) Deserialization of Untrusted Data vulnerability in org.apache.activemq:activemq-client. It is in CISA's Known Exploited Vulnerabilities catalog (added 2023-11-02) and has been used in ransomware campaigns — treat it as actively exploited and patch now. O3 Security confirms whether GHSA-crg9-44h2-xw35 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Apache ActiveMQ is vulnerable to Remote Code Execution
Exploitation Status
Actively exploited in the wild
- Confirmed by CISA's Known Exploited Vulnerabilities catalog on 2023-11-02 — including use in ransomware campaigns. Federal agencies were required to remediate by 2023-11-23.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- A successful exploit gives an attacker total control of the affected component, not partial access.
Exploitation and automatability from CISA (KEV catalog and SSVC triage) for GHSA-crg9-44h2-xw35.
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.
How urgent is this, really
GHSA-crg9-44h2-xw35 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE sits: patch-first territory.
Where this sits among everything scored
Of 368,770 CVEs with a current EPSS score, this one falls in the ≥ 90% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
org.apache.activemq:activemq-client☕org.apache.activemq:activemq-client☕org.apache.activemq:activemq-client☕org.apache.activemq:activemq-client☕org.apache.activemq:activemq-openwire-legacy☕org.apache.activemq:activemq-openwire-legacy☕org.apache.activemq:activemq-openwire-legacy☕org.apache.activemq:activemq-openwire-legacyReal-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
Apache ActiveMQ is vulnerable to Remote Code Execution.The vulnerability may allow a remote attacker with network access to a broker to run arbitrary shell commands by manipulating serialized class types in the OpenWire protocol to cause the broker to instantiate any class on the classpath.
Users are recommended to upgrade to version 5.15.16, 5.16.7, 5.17.6, or 5.18.3, which fixes this issue.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | org.apache.activemq:activemq-client | all versions | 5.15.16 |
| ☕Maven | org.apache.activemq:activemq-client | ≥ 5.16.0&&< 5.16.7 | 5.16.7 |
| ☕Maven | org.apache.activemq:activemq-client | ≥ 5.17.0&&< 5.17.6 | 5.17.6 |
| ☕Maven | org.apache.activemq:activemq-client | ≥ 5.18.0&&< 5.18.3 | 5.18.3 |
| ☕Maven | org.apache.activemq:activemq-openwire-legacy | ≥ 5.8.0&&< 5.15.16 | 5.15.16 |
| ☕Maven | org.apache.activemq:activemq-openwire-legacy | ≥ 5.16.0&&< 5.16.7 | 5.16.7 |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
The Java OpenWire protocol marshaller is vulnerable to Remote Code Exec…
The Java OpenWire protocol marshaller is vulnerable to Remote Code Exec…
The Java OpenWire protocol marshaller is vulnerable to Remote Code Exec…
The Java OpenWire protocol marshaller is vulnerable to Remote Code Exec…
The Java OpenWire protocol marshaller is vulnerable to Remote Code Exec…
The Java OpenWire protocol marshaller is vulnerable to Remote Code Exec…
The Java OpenWire protocol marshaller is vulnerable to Remote Code Exec…
The Java OpenWire protocol marshaller is vulnerable to Remote Code Exec…
The Java OpenWire protocol marshaller is vulnerable to Remote Code Exec…
The Java OpenWire protocol marshaller is vulnerable to Remote Code Exec…
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.apache.activemq:activemq-client. 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.activemq:activemq-client to 5.15.16 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-crg9-44h2-xw35 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 GHSA-crg9-44h2-xw35 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 GHSA-crg9-44h2-xw35. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
If the openwire protocol IS NOT in use, system operators can disable the OpenWire protocol which removes most risk of this vulnerability being exploited. If OpenWire IS being used, see the Mitigations section for potential options to reduce your attack surface. * How to determine if an AMQ 7 system is affected: Check…
Frequently Asked Questions
Is GHSA-crg9-44h2-xw35 in your dependencies?
O3 detects GHSA-crg9-44h2-xw35 across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.