CVE-2026-91006: Command Injection (CVSS 8.8)

Description

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.

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CVSS v3.1 Score

8.8

HIGH

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS — Exploit Prediction

0.0114

Probability of exploitation

0.66%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-78 OS Command Injection

References

Other References

https://lists.apache.org/thread/olzy0yjw82b20w59vonfjr1x7v5yzocr http://www.openwall.com/lists/oss-security/2026/09/28/3

Frequently Asked Questions

What is CVE-2026-91006? +

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. It has a CVSS v3.1 base score of 8.8 (HIGH).

How severe is CVE-2026-91006? +

CVE-2026-91006 has a CVSS v3.1 score of 8.8 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0114, placing it in the 1th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-91006? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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