CriticalCVE-2016-8735

    Apache Tomcat Remote Code Execution Vulnerability (CVE-2016-8735)

    Published Last modified In CISA KEV since Sources: OSV, CVE.org

    What is affected, what to do

    Remote code execution is possible with Apache Tomcat before 6.0.48, 7.x before 7.0.73, 8.x before 8.0.39, 8.5.x before 8.5.7, and 9.x before 9.0.0.M12 if JmxRemoteLifecycleListener is used and an attacker can reach JMX ports. The issue exists because this listener wasn't updated for consistency with the CVE-2016-3427 Oracle patch that affected credential types.

    The vulnerability is being actively exploited; treat it as a priority. Update tomcat to version 8.0.39. Immediate actions, mitigation and detection rules are in the runbook below.

    Affected
    • Apache Tomcat eq before 6.0.48..before 6.0.48
    • Apache Tomcat eq 7.x before 7.0.73..7.x before 7.0.73
    • Apache Tomcat eq 8.x before 8.0.39..8.x before 8.0.39
    • Apache Tomcat eq 8.5.x before 8.5.7..8.5.x before 8.5.7
    • Apache Tomcat eq 9.x before 9.0.0.M12..9.x before 9.0.0.M12

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

    Metrics

    9.8

    Priority

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

    Source: NVD, CVSS v3

    9.8

    CVSS v3

    Severity Critical on the scale from 0 to 10.

    Source: OSV, CVE.org

    90.3 %

    EPSS score

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

    Source: FIRST EPSS, percentile 99.80

    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
    228.68 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 exploited
    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
    9.8 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
    9.8
    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
    90.3 %
    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
    99.80
    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

    Response and mitigation

    Why act now?

    Prioritisation rationale

    This flaw is network-reachable without authentication and gives direct code execution as the Tomcat service account. It sits among the CVEs most likely to be exploited, and off-the-shelf deserialisation tooling makes weaponisation trivial. CISA does not flag known ransomware use. Typical victims are legacy Tomcat estates where JMX was opened "temporarily" for monitoring and never closed, frequently inside line-of-business applications or vendor appliances that bundle Tomcat. If the listener is enabled and the JMX port is reachable from the internet or broad internal networks, treat this as critical with a 24-hour remediation target. If JMX is disabled or strictly confined to localhost or a management VLAN, the risk drops sharply and patching can follow the regular maintenance cycle.

    1. Runbook step 1

      Immediate response (0-24 h)

      • Determine exposure: Search every Tomcat instance's conf/server.xml for JmxRemoteLifecycleListener (grep -R "JmxRemoteLifecycleListener" $CATALINA_BASE/conf/) and check whether catalina-jmx-remote.jar is present in lib/. Only instances with the listener enabled are affected. Treat them as top priority.
      • Lock down JMX ports now: Block the ports set in server.xml (rmiRegistryPortPlatform / rmiServerPortPlatform, 10001/10002 in the docs example) and 1099/TCP where used, at both perimeter and host firewall, for all unauthorised source networks. Internet-facing instances come first, so check your own IP ranges against Shodan/Censys.
      • Apply the vendor fix: Upgrade to at least Tomcat 6.0.48, 7.0.73, 8.0.39, 8.5.7 or 9.0.0.M12. Branches 6.x, 7.x, 8.0.x and 8.5.x are end-of-life, so migrate to a currently supported Tomcat branch rather than just the minimum fixed build.
      • Remove the listener if unused: Delete or comment out the <Listener className="org.apache.catalina.mbeans.JmxRemoteLifecycleListener" … /> entry and restart Tomcat. Move monitoring to local JMX or an agent bound to localhost.
      • Compromise assessment: On hosts whose JMX ports were reachable, hunt for web shells in webapps/, rogue cron jobs or services, and child processes of the Tomcat JVM. If you find anything, isolate the host and rotate the Tomcat service account credentials and any DB/application secrets held in context.xml.

    2. Runbook step 2

      Mitigation layers

      • Network segmentation: Permit JMX/RMI only from a dedicated management VLAN or monitoring jump hosts. Apply default-deny for inbound traffic to the configured RMI ports from server and client networks.
      • Bind to loopback: Set useLocalPorts="true" on the listener so the ports listen on localhost only. Allow remote access exclusively through SSH tunnels.
      • Authentication alone is not enough: The flaw lies in how credential types are handled before authentication completes. Keep com.sun.management.jmxremote.authenticate=true plus SSL, but neither replaces patching or network restriction.
      • JVM hardening: Run a current JDK that includes Oracle's fix for CVE-2016-3427. Define an allow-list deserialisation filter (jdk.serialFilter / JEP 290, where the JVM supports it). Strip known gadget libraries, such as old commons-collections, from the classpath.
      • IPS rule: Alert on and block Java RMI handshakes (content:"|4A 52 4D 49|" = "JRMI") and serialised Java objects (content:"|AC ED 00 05|") heading to Tomcat hosts from unauthorised sources.
      • Least privilege: Run Tomcat as an unprivileged service account with no login shell and no write access to conf/ or lib/, to limit the blast radius of successful code execution.

    3. Runbook step 3

      Detection rules

      • Network telemetry (Zeek/Suricata): Flag connections to JMX/RMI ports from sources outside the monitoring allow-list, especially payloads containing JRMI followed by AC ED 00 05, which is typical of ysoserial gadget chains. Zeek: conn.log where id.resp_p in {1099,10001,10002} and id.orig_h is not allow-listed.
      • Process ancestry (Sysmon EID 1 / EDR): Watch for java/java.exe with catalina on the command line spawning shells or LOLBins. KQL: DeviceProcessEvents | where InitiatingProcessFileName =~ "java.exe" and InitiatingProcessCommandLine has "catalina" and FileName in~ ("cmd.exe","powershell.exe","certutil.exe","bitsadmin.exe").
      • Linux auditd: Look for execve events whose parent is the Tomcat user's java process and whose exe is /bin/sh, /bin/bash, /usr/bin/curl or /usr/bin/wget. Sigma shape: ParentImage|endswith: '/java' and Image|endswith: ['/sh','/bash','/curl','/wget'].
      • Filesystem (Sysmon EID 11 / auditd -w): Alert on new .jsp/.jspx files in webapps/ or work/ outside deployment windows, and on modifications to server.xml or tomcat-users.xml.
      • Egress (Sysmon EID 3): Alert when the Tomcat process opens unexpected outbound connections to the internet, such as reverse shells, payload staging or mining pools.

    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

    Remote code execution is possible with Apache Tomcat before 6.0.48, 7.x before 7.0.73, 8.x before 8.0.39, 8.5.x before 8.5.7, and 9.x before 9.0.0.M12 if JmxRemoteLifecycleListener is used and an attacker can reach JMX ports. The issue exists because this listener wasn't updated for consistency with the CVE-2016-3427 Oracle patch that affected credential types.

    Source: OSV (Open Source Vulnerabilities), cvelistv5, CISA KEV Catalog, NVD (NIST), CVE.org (MITRE)

    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 Tomcat
    • 7.x before 7.0.73
    • 9.x before 9.0.0.M12
    • before 6.0.48
    • 8.5.x before 8.5.7
    • 8.x before 8.0.39
    • —
    • —
    • —
    • —
    • —
    apachetomcat
    • 9.0.0
    • 8.0 – < 8.0.39
    • 7.0.0 – < 7.0.73
    • 8.5.0 – < 8.5.7
    • < 6.0.48
    • —
    • 8.0.39
    • 7.0.73
    • 8.5.7
    • 6.0.48
    netapp7-mode_transition_tool
    • —
    • —
    netapponcommand_insight
    • —
    • —
    netapponcommand_shift
    • —
    • —
    netappsnap_creator_framework
    • —
    • —
    oracleagile_engineering_data_management
    • 6.2.0
    • 6.2.1.0
    • 6.1.3
    • —
    • —
    • —
    oracleagile_product_lifecycle_management
    • 9.3.5
    • 9.3.6
    • —
    • —
    oraclecommunications_application_session_controller
    • 3.8.0
    • 3.7.1
    • —
    • —
    oraclecommunications_instant_messaging_server
    • 10.0.1
    • —
    oraclecommunications_interactive_session_recorder
    • 6.1
    • 6.2
    • 6.0
    • —
    • —
    • —
    oraclehospitality_guest_access
    • 4.2.0
    • 4.2.1
    • —
    • —
    oraclemicros_relate_crm_software
    • 10.8
    • 11.4
    • —
    • —
    oraclemicros_retail_xbri_loss_prevention
    • 10.5.0
    • 10.0.1
    • 10.6.0
    • 10.8.0
    • 10.7.7
    • 10.8.1
    • —
    • —
    • —
    • —
    • —
    • —
    oraclemysql_enterprise_monitor
    • 3.3.0 – ≤ 3.3.4.3247
    • 3.4.0 – ≤ 3.4.2.4181
    • ≤ 3.2.8.2223
    • —
    • —
    • —
    oracleretail_convenience_and_fuel_pos_software
    • 2.1.132
    • —
    oracletransportation_management
    • 6.3.5
    • 6.3.1
    • 6.3.4
    • 6.3.3
    • 6.3.6
    • 6.3.7
    • 6.3.0
    • 6.3.2
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    redhatjboss_enterprise_web_server
    • 3.0.0
    • —

    Vendors and products

    Affected operating systems

    Affected operating systems
    Linuxdebiandebian_linux8.0
    Linuxcanonicalubuntu_linux16.04

    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

    References & sources

    • NVD (NIST)vuln/detail/CVE-2016-8735advisory
    • github.comapache/tomcat/commit/0e83ad3e547fc9a75a258799ef581249b40a82a6web
    • github.comapache/tomcat/commit/292d6ccdc9edbf80859929b0af070b2ea99fa688web
    • github.comapache/tomcat/commit/7e3a037055cca4a17e90b49399fb1bab4dd7c821web
    • github.comapache/tomcat80/commit/0f76016a4ec45635e450ada9c84ff7ee0c5f3799web
    • lists.apache.org[tomcat-dev] 20190325 svn commit: r1856174 [24/29] - in /tomcat/site/trunk: docs/ xdocs/ xdocs/stylesheets/web, Mailing list, x_refsource_MLIST
    • lists.apache.orgthread.html/b5e3f51d28cd5d9b1809f56594f2cf63dcd6a90429e16ea9f83…web
    • lists.apache.org[tomcat-dev] 20190415 svn commit: r1857582 [16/22] - in /tomcat/site/trunk: docs/ xdocs/stylesheets/web, Mailing list, x_refsource_MLIST
    • lists.apache.orgthread.html/b84ad1258a89de5c9c853c7f2d3ad77e5b8b2930be9e132d5ce…web
    • lists.apache.org[tomcat-dev] 20190319 svn commit: r1855831 [23/30] - in /tomcat/site/trunk: ./ docs/ xdocs/web, Mailing list, x_refsource_MLIST
    • lists.apache.orgthread.html/b8a1bf18155b552dcf9a928ba808cbadad84c236d85eab30336…web
    • lists.apache.org[tomcat-dev] 20200203 svn commit: r1873527 [23/30] - /tomcat/site/trunk/docs/web, Mailing list, x_refsource_MLIST
    • lists.apache.orgthread.html/r03c597a64de790ba42c167efacfa23300c3d6c9fe589ab87fe…web
    • lists.apache.org[tomcat-dev] 20200213 svn commit: r1873980 [26/34] - /tomcat/site/trunk/docs/web, Mailing list, x_refsource_MLIST
    • lists.apache.orgthread.html/r587e50b86c1a96ee301f751d50294072d142fd6dc08a8987ae…web
    • lists.apache.org[tomcat-dev] 20200213 svn commit: r1873980 [27/34] - /tomcat/site/trunk/docs/web, Mailing list, x_refsource_MLIST
    • lists.apache.orgthread.html/r9136ff5b13e4f1941360b5a309efee2c114a14855578c3a2cb…web
    • security.netapp.comadvisory/ntap-20180607-0001web
    • usn.ubuntu.com4557-1web
    • web.archive.orgweb/20170423095340/http://www.securityfocus.com/bid/94463web

    Changes to this CVE

    Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).

    1. Product identifiers remappedNVD

      Product mapping changed:
      Show the original change
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Product configurationchanged
      OR *cpe:2.3:a:oracle:agile_plm:9.3.5:*:*:*:*:*:*:*
      OR *cpe:2.3:a:oracle:agile_product_lifecycle_management:9.3.5:*:*:*:*:*:*:*

      Source identifier: nvd@nist.gov

    2. Product identifiers remappedNVD

      Product mapping changed:
      Show the original change
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Product configurationchanged
      OR *cpe:2.3:a:oracle:agile_plm:9.3.6:*:*:*:*:*:*:*
      OR *cpe:2.3:a:oracle:agile_product_lifecycle_management:9.3.6:*:*:*:*:*:*:*

      Source identifier: nvd@nist.gov

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