+44 1865 950 828 Secure Your Business
Actively exploitedKnown ransomware use

CVE-2023-46604 Apache ActiveMQ Deserialization of Untrusted Data Vulnerability

Apache ActiveMQ contains a deserialization of untrusted data vulnerability that may allow a remote attacker with network access to a broker to run shell commands by manipulating serialized class types in the OpenWire protocol to cause the broker to instantiate any class on the classpath.

From the CISA KEV catalogue version 2026.11.06, with Cybergen analysis. Updated 6 Nov 2026.

Our Assessment

Should You Worry?

Patch nowCybergen assessment
  • CISA confirmed exploitation in the wild and added it to the Known Exploited Vulnerabilities catalogue on 2 Nov 2023.
  • CISA lists it as known to be used in ransomware campaigns.
  • Rated Critical severity (CVSS 10.0, scored by Vendor).
  • It has been in the catalogue for 1,100 days. Systems still unpatched now have almost certainly been scanned for it.
The Vulnerability

What It Is

The Java OpenWire protocol marshaller is vulnerable to Remote Code Execution. This vulnerability may allow a remote attacker with network access to either a Java-based OpenWire broker or client to run arbitrary shell commands by manipulating serialized class types in the OpenWire protocol to cause either the client or the broker (respectively) to instantiate any class on the classpath. Users are recommended to upgrade both brokers and clients to version 5.15.16, 5.16.7, 5.17.6, or 5.18.3 which fixes this issue.

Affected Versions

ProductVersions
Apache Software Foundation Apache ActiveMQ5.18.0 to before 5.18.3
5.17.0 to before 5.17.6
5.16.0 to before 5.16.7
before 5.15.16
Apache Software Foundation Apache ActiveMQ Legacy OpenWire Module5.18.0 to before 5.18.3
5.17.0 to before 5.17.6
5.16.0 to before 5.16.7
5.8.0 to before 5.15.16

From the public CVE record, as supplied by the vendor. Always confirm against the vendor advisory.

From Watch to Action

What To Do Now

  1. 1

    Find it

    Search your asset inventory and external attack surface for Apache ActiveMQ. Include cloud images, appliances and anything a supplier runs for you.

    Attack Surface Management
  2. 2

    Fix it

    Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

    Vulnerability Management
  3. 3

    Hunt for compromise

    If an affected system was reachable before you patched, assume it may have been hit. Check logs, new accounts, web shells and outbound connections from the date of exposure.

    Incident Response
  4. 4

    Prove it is fixed

    Rescan or test the system after patching. Upgrades that fail silently and forgotten secondary instances are common.

    Penetration Testing

Vendor Advisories

Regulation

The Compliance Clock

Cyber EssentialsRated critical, so if it affects devices in your Cyber Essentials scope, the update must be installed within 14 days of the vendor releasing it.NIS2If exploitation causes a significant incident, essential and important entities owe their CSIRT an early warning within 24 hours and a notification within 72 hours.DORAFinancial entities must classify ICT incidents and send an initial notification for a major incident within strict deadlines, with exploited flaws a common cause.US federal (BOD 22-01)Federal civilian agencies had until 23 Nov 2023 to remediate. A sensible benchmark for everyone else.

General guidance, not legal advice. Your obligations depend on your sector, scope and jurisdiction.

Stay Ahead

More Exploited Apache Flaws

Get alerts for ApacheWe email you when a new Apache vulnerability is confirmed as exploited. Add more vendors on Threat Watch.

By signing up you agree to receive Threat Watch alerts. Unsubscribe at any time. See our Privacy Policy.

CVE-2016-3081Apache Struts Command Injection VulnerabilityAdded 8 Oct 2026CVE-2026-34486Apache Tomcat Missing Encryption of Sensitive Data VulnerabilityAdded 4 Aug 2026CVE-2026-34197Apache ActiveMQ Improper Input Validation VulnerabilityAdded 16 Apr 2026CVE-2024-38475Apache HTTP Server Improper Escaping of Output VulnerabilityAdded 1 May 2025CVE-2025-24813Apache Tomcat Path Equivalence VulnerabilityAdded 1 Apr 2025CVE-2024-45195Apache OFBiz Forced Browsing VulnerabilityAdded 4 Feb 2025

All 41 exploited Apache vulnerabilities

Not Sure If You Are Exposed?

Our attack surface and vulnerability teams can check your internet-facing estate for CVE-2023-46604 and every other exploited flaw on the list.

Check My Exposure
Evidence

Sources

  1. CISA Known Exploited Vulnerabilities catalogue
  2. NVD: CVE-2023-46604
  3. CVE record: CVE-2023-46604
  4. FIRST EPSS
  5. activemq.apache.org/security-advisories.data/CVE-2023-46604-announcement.txt
  6. openwall.com/lists/oss-security/2023/10/27/5
  7. security.netapp.com/advisory/ntap-20231110-0010/
  8. packetstormsecurity.com/files/175676/Apache-ActiveMQ-Unauthenticated-Remote-Code-Execution.html
  9. lists.debian.org/debian-lts-announce/2023/11/msg00013.html
  10. seclists.org/fulldisclosure/2024/Apr/18