CriticalCVE-2023-46604

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

    Published In CISA KEV since Sources: SingCERT, Debian, pwn.watch, CVE.org, OSV, BSI

    What is affected, what to do

    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.

    The vulnerability is being actively exploited; treat it as a priority. CISA lists it as used in ransomware campaigns. Update Apache ActiveMQ to version 5.18.3, Apache ActiveMQ to version 5.17.6, Apache ActiveMQ to version 5.16.7. Immediate actions, mitigation and detection rules are in the runbook below.

    Affected
    • Apache ActiveMQ lt 5.18.0..5.18.3
    • Apache ActiveMQ lt 5.17.0..5.17.6
    • Apache ActiveMQ lt 5.16.0..5.16.7
    • Apache ActiveMQ lt *..5.15.16
    • Apache ActiveMQ Legacy OpenWire Module lt 5.18.0..5.18.3
    • Apache ActiveMQ Legacy OpenWire Module lt 5.17.0..5.17.6
    • Apache ActiveMQ Legacy OpenWire Module lt 5.16.0..5.16.7
    • Apache ActiveMQ Legacy OpenWire Module lt 5.8.0..5.15.16
    Fixed in
    • Apache ActiveMQ 5.18.3
    • Apache ActiveMQ 5.17.6
    • Apache ActiveMQ 5.16.7
    • Apache ActiveMQ 5.15.16
    • Apache ActiveMQ Legacy OpenWire Module 5.18.3
    • Apache ActiveMQ Legacy OpenWire Module 5.17.6
    • Apache ActiveMQ Legacy OpenWire Module 5.16.7
    • Apache ActiveMQ Legacy OpenWire Module 5.15.16

    Not sure whether and how you are affected? Ask a question about this vulnerability

    Metrics

    10.0

    Priority

    XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.

    Source: Vendor (CNA), CVSS v3

    10.0

    CVSS v3

    Severity Critical on the scale from 0 to 10.

    Source: SingCERT, Debian, pwn.watch, CVE.org, OSV, BSI

    99.89 %

    EPSS score

    High — model estimates ≥ 50% chance of real-world exploitation within 30 days.

    Source: FIRST EPSS, percentile 99.97

    Show all metrics
    Severity
    Critical
    Priority (0–325)

    The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?

    Read in glossary
    258.68 Methodology
    Exploit maturity

    An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.

    Read in glossary
    actively exploitedSource: CSA/SingCERT How we classify
    XIEM Effective CVSS

    XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.

    Read in glossary
    10.0 Methodology
    CVSS v3

    CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.

    Read in glossary
    10.0
    EPSS score

    The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“.

    Read in glossary
    99.89 %
    High — model estimates ≥ 50% chance of real-world exploitation within 30 days.
    EPSS percentile

    The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking.

    Read in glossary
    99.97
    Critical — this CVE ranks in the top fifth of all CVEs scored today (rank ≥ 80%).
    KEV status

    The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.

    Read in glossary
    Actively exploited
    Published
    In CISA KEV since

    The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.

    Read in glossary
    CWE

    CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect.

    Read in glossary
    CWE-502

    Response and mitigation

    Why act now?

    Prioritisation rationale

    This flaw is network-reachable without authentication, trivial to trigger, and gives full code execution as the broker process. Public exploits have circulated since late 2023, it sits among the CVEs most likely to be exploited, and CISA flags known use in ransomware campaigns; it has also been abused for cryptomining and botnet deployment. Typical victims are middleware servers in manufacturing, logistics, healthcare and finance, which are often treated as "internal" plumbing and left unpatched. Treat any broker reachable from untrusted networks as an emergency and assume compromise until proven otherwise. Internal-only brokers belong at the very top of the regular patch queue, because they are a prime lateral-movement target once an attacker has a foothold. NIS2/KRITIS operators should start their reporting-deadline clock as soon as exploitation is confirmed.

    1. Runbook step 1

      Immediate response (0-24 h)

      • Patch now: Upgrade every ActiveMQ broker and every Java OpenWire client (the activemq-client JAR bundled in applications, plus the Legacy OpenWire Module) to 5.15.16, 5.16.7, 5.17.6 or 5.18.3. Releases older than 5.15 have no fix in their branch, so they must be migrated to a supported line.
      • Cut exposure: Block OpenWire on TCP 61616 at the perimeter, along with any TLS/NIO OpenWire transports defined under transportConnectors in activemq.xml. Take internet-facing brokers offline or put them behind a VPN until they are patched.
      • Inventory: Use asset scanning or EDR to find every host listening on 61616 and every Java process with activemq in its command line. Include embedded brokers inside applications, such as Spring Boot apps that ship activemq-broker.
      • Compromise assessment: On any broker that was exposed before patching, review child processes of the broker JVM, new cron jobs or scheduled tasks, files dropped in /tmp, /var/tmp or %TEMP%, and any new local accounts. If you find anything, isolate the host and take a forensic image before rebuilding.
      • Rotate secrets: If compromise is suspected, rotate everything stored on the broker. This covers credentials in activemq.xml, jetty-realm.properties and credentials.properties, JDBC persistence passwords, and any service-account keys on the host.

    2. Runbook step 2

      Mitigation layers

      • Network segmentation: Allow OpenWire only from defined application VLANs, using an allowlist of producer and consumer IPs. Default-deny outbound internet traffic from broker hosts, because the known exploit chain fetches a remote XML config over HTTP(S).
      • IPS rule: Add a signature on TCP 61616 for OpenWire frames that carry org.springframework.context.support.ClassPathXmlApplicationContext or FileSystemXmlApplicationContext. Example Suricata rule: alert tcp any any -> $HOME_NET 61616 (msg:"CVE-2023-46604 ActiveMQ OpenWire RCE"; flow:to_server,established; content:"XmlApplicationContext"; nocase; sid:9004660; rev:1;). Enable the vendor rulesets (ET Open/Pro, Talos) as well.
      • Endpoint hardening: Run the broker under a dedicated, unprivileged, non-login service account. Use AppArmor/SELinux or WDAC/AppLocker to stop the broker JVM from spawning sh, bash, curl, wget, cmd.exe, powershell.exe or certutil.exe.
      • Configuration: Disable transport connectors you don't need, and where feasible, use authenticated TLS transports with client certificates. Note that authentication alone does not mitigate this flaw, because the unsafe deserialisation happens before login.
      • Client side: Java applications that use OpenWire clients are exposed when they connect to a rogue or compromised broker. Run SCA tooling (Dependency-Track, OWASP Dependency-Check) to find vulnerable activemq-client versions.

    3. Runbook step 3

      Detection rules

      • EDR process ancestry: Alert when the broker JVM spawns a shell or downloader. KQL: DeviceProcessEvents | where InitiatingProcessFileName in~ ("java","java.exe") and InitiatingProcessCommandLine has "activemq" and FileName in~ ("sh","bash","curl","wget","cmd.exe","powershell.exe","certutil.exe")
      • Linux auditd / Sysmon: On Linux, watch for execve events whose ppid is the ActiveMQ process and whose exe is /bin/sh, /usr/bin/curl or /usr/bin/wget. On Windows, watch for Sysmon EID 1 where ParentImage is java.exe and ParentCommandLine references ActiveMQ.
      • Broker logs: Search data/activemq.log for stack traces or warnings that mention ClassPathXmlApplicationContext, FileSystemXmlApplicationContext or ExceptionResponse. SPL: index=app sourcetype=activemq ("XmlApplicationContext" OR "ExceptionResponse")
      • Network telemetry (Zeek/proxy): Look for outbound HTTP from broker hosts that retrieves .xml files from external IPs, followed shortly by downloads of scripts or binaries. In Zeek http.log, filter on uri ending in .xml with a source IP in the broker subnet.
      • Persistence and pre-ransomware activity: Watch for new files under the ActiveMQ web console's webapps/ directory, and for Windows Event IDs 4720 and 7045 or changes to /etc/crontab on broker hosts. Shadow-copy deletion (vssadmin delete shadows) is a strong late-stage signal.

    Detection rules

    No NEOSEC detection rule is available for this vulnerability yet.

    Classification under NIS2 and CRA

    Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

    NIS2

    NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.

    Read in glossary
    Actively exploited: treat the vulnerability as a priority in vulnerability handling under Art. 21(2)(e) NIS2. If it is exploited in your environment, check the reporting obligation under Art. 23 (early warning within 24 hours).
    CRA

    The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.

    Read in glossary
    Since 11.09.2026, manufacturers of affected products with digital elements must report actively exploited vulnerabilities under Art. 14 CRA, with an early warning within 24 hours via ENISA's single reporting platform.
    ISO/IEC 27001

    ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.

    Read in glossary
    Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

    Description

    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.

    Source: CSA/SingCERT, Debian Security Advisories, pwn.watch, NVD (NIST), OSV (Open Source Vulnerabilities), cvelistv5, CISA KEV Catalog, CVE.org (MITRE), BSI WID Portal, BSI CSAF

    Affected products

    The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

    Affected products
    Affected versionsFixed in
    Apache Software FoundationApache ActiveMQ
    • 5.17.0 – < 5.17.6
    • 5.16.0 – < 5.16.7
    • 5.18.0 – < 5.18.3
    • < 5.15.16
    • 5.17.6
    • 5.16.7
    • 5.18.3
    • 5.15.16
    Apache Software FoundationApache ActiveMQ Legacy OpenWire Module
    • 5.16.0 – < 5.16.7
    • 5.18.0 – < 5.18.3
    • 5.8.0 – < 5.15.16
    • 5.17.0 – < 5.17.6
    • 5.16.7
    • 5.18.3
    • 5.15.16
    • 5.17.6
    apacheactivemq
    • 5.17.0 – < 5.17.6
    • 5.16.0 – < 5.16.7
    • 5.18.0 – < 5.18.3
    • < 5.15.16
    • 5.17.6
    • 5.16.7
    • 5.18.3
    • 5.15.16
    apacheactivemq_legacy_openwire_module
    • 5.17.0 – < 5.17.6
    • 5.16.0 – < 5.16.7
    • 5.18.0 – < 5.18.3
    • < 5.15.16
    • 5.17.6
    • 5.16.7
    • 5.18.3
    • 5.15.16
    netappe-series_santricity_unified_manager
    • —
    • —
    netappe-series_santricity_web_services_proxy
    • —
    • —
    netappsantricity_storage_plugin
    • —
    • —
    OracleCommunications
    • 24.2.0
    • 9.3.0
    • 24.1.1
    • 9.2.0
    • 23.4.4
    • 8.1
    • 5.2
    • 4.1.0
    • 24.2.1
    • 47.0.0.0.0
    • 9
    • 9.0.0.0.0
    • 15.0.0.0.0
    • 24.3.0
    • 5.1
    • 8.6.0.4.0
    • 24.2.3
    • 15
    • 24.1.0
    • 8
    • 12.11
    • 14
    • 23.4.0
    • 4.2.0
    • 8.2.3.0.0
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    mavenorg.apache.activemq:activemq-client
    • 5.17.4
    • 5.16.4
    • 5.12.2
    • 5.11.4
    • —
    • —
    • —
    • —

    Vendors and products

    Affected operating systems

    Affected operating systems
    Linuxdebianactivemqbookworm
    Linuxdebiandebian_linux10.0
    Linuxdebiandebian_linux11.0

    Weakness classes (CWE)

    • CWE-502Deserialization of Untrusted Data

      Base

      The product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid.

      Entry at MITRE CWE-502

    Public exploit references

    Publicly reported proof-of-concepts, exploit modules and detection templates for this vulnerability. NEOSEC links to the original sources only and does not provide any exploit code.

    Public exploit references
    CISA KEV CatalogCISA Known Exploited Vulnerability (opens in a new tab)cisa.govactively exploited
    CSA/SingCERTActive Exploitation of Critical Vulnerability in Apache ActiveMQ (opens in a new tab)CSA/SingCERTactively exploited
    Packet StormApache ActiveMQ Unauthenticated Remote Code Execution (opens in a new tab)packetstormsecurity.comPoC (publicly reported)reported, not verified—
    PoC-in-GitHub (nomi-sec)vulhub-activemq-cve-2023-46604 (opens in a new tab)github.comPoC (publicly reported)reported, not verified
    PoC-in-GitHub (nomi-sec)ActiveMQ-CVE-2023-46604 (opens in a new tab)github.comPoC (publicly reported)reported, not verified
    PoC-in-GitHub (nomi-sec)CVE-2023-46604-RCE (opens in a new tab)github.comPoC (publicly reported)reported, not verified

    References & sources

    • NVD (NIST)NVD: CVE-2023-46604advisory, pwn-watch
    • github.comapache/activemq/pull/1098web
    • github.comapache/activemq/commit/22442b2385b1000312aec3d19e510131d595a5fcweb
    • github.comapache/activemq/commit/80089f9f476afab7d976f5fc37c5ab4aa0c2139dweb
    • github.comapache/activemq/commit/958330df26cf3d5cdb63905dc2c6882e98781d8fweb
    • github.comapache/activemq/commit/9905e2a5bf9862a049f94ce0a2465b0c7ad52436web
    • github.comapache/activemq/commit/d0ccdd31544ada83185554c87c7aa141064020f0web
    • openwall.comlists/oss-security/2023/10/27/5web, Mailing list
    • cisa.govknown-exploited-vulnerabilities-catalog?field_cve=CVE-2023-46604web, government-resource, Third-party advisory, US government resource
    • security.netapp.comadvisory/ntap-20231110-0010web
    • packetstormsecurity.comfiles/175676/Apache-ActiveMQ-Unauthenticated-Remote-Code-Execut…web, Exploit, Third-party advisory, Vulnerability database
    • lists.debian.orgdebian-lts-announce/2024/10/msg00027.htmlweb, Mailing list
    • lists.debian.orgdebian-lts-announce/2023/11/msg00013.htmlweb, Mailing list
    • issues.apache.orgjira/browse/AMQ-9370web
    • github.comapache/activemqpackage
    • activemq.apache.orgCVE-2023-46604 announcementweb, Vendor advisory, Vendor advisory, pwn-watch
    • activemq.apache.orgsecurity-advisories.data/CVE-2023-46604web
    • packetstormsecurity.comfiles/175676/Apache-ActiveMQ-Unauthenticated-Remote-Code-Execut…web
    • seclists.orgfulldisclosure/2024/Apr/18web, Mailing list, Third-party advisory
    • openwall.comlists/oss-security/2023/10/27/5web
    Embed badge

    Show the severity and KEV status of this vulnerability on your site – with a link back here. The image is updated hourly.

    Badge preview for CVE-2023-46604
    <a href="https://intel.neosec.eu/en/cve/CVE-2023-46604"><img src="https://intel.neosec.eu/badge/cve/CVE-2023-46604.svg?lang=en" alt="CVE-2023-46604 – NEOSEC Intel" height="20"></a>