Bug 2542423 (CVE-2026-91006)

Summary: CVE-2026-91006 org.apache.karaf.instance/org.apache.karaf.instance.core: karaf: Apache Karaf: Arbitrary command execution via unquoted instance options
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
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Severity: high Docs Contact:
Priority: high    
Version: unspecifiedCC: gmalinko, janstey, pdelbell, rstepani
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in Apache Karaf. An attacker with access to instance-management commands or Java Management Extensions (JMX) interfaces can achieve arbitrary command execution on the underlying host system. This issue occurs because user-supplied Java options are spliced directly into child-instance launch commands without proper quoting or validation, allowing shell metacharacters to be interpreted and run with the privileges of the Karaf process user.
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Description OSIDB Bzimport 2026-09-28 10:52:12 UTC 
Apache Karaf's instance-management service (InstanceServiceImpl) builds the command line used to launch a child Karaf JVM by string concatenation, then executes it through /bin/sh (Unix) or cscript (Windows). The caller-supplied javaOpts value is spliced into that string unquoted. A javaOpts value containing shell metacharacters (;, |, `, $(...)) is interpreted by the shell instead of being passed to the JVM as an option, giving arbitrary OS command execution as the Karaf process user.


Reachable via the shell commands instance:create, instance:start, instance:restart, instance:change-opts, and the equivalent InstanceMBean JMX operations (createInstance, startInstance, changeJavaOpts, cloneInstance).

Mitigation   *  Set karaf.secured.command.compulsory.roles=admin in etc/system.properties to close the fail-open gap for all unconfigured command scopes.
  *  Restrict which principals can reach instance:* commands and InstancesMBean via etc/users.properties role assignments.
  *  Treat javaOpts passed to instance:create/instance:start/instance:change-opts/InstancesMBean as untrusted input only from fully-trusted operators.