AI analysis
Apache Karaf enforces shell and SSH command security with per-scope ACL files, but when no ACL rule matches a command the check fails open and the command is allowed for any authenticated user. The shipped config command ACL has no entry for config:install, so a user with only the viewer role can run it. config:install downloads a URL and writes the result into the Karaf etc directory, and with override can replace security files such as users, keys, and ACL configuration; Felix FileInstall reloads .cfg files from that directory without a restart, enabling privilege escalation to admin. Other install commands and config:delete are restricted to admin; config:install is the exception. No public proof of concept is known, it is not listed in CISA KEV, and exploitation in the wild is not reported.
What to do: Add an install = admin rule to etc/org.apache.karaf.command.acl.config.cfg (create the file if it is missing) and/or set karaf.secured.command.compulsory.roles=admin in etc/system.properties, then restart so unmatched commands fail closed. Review ${karaf.etc} for unexpected or overwritten files (users.properties, keys.properties, host.key, and org.apache.karaf.*.acl.* / .cfg files) and restrict Karaf shell/SSH to trusted administrators.
Estimated exposure
—No basis for an estimate.
Order-of-magnitude estimate by the model from install counts, market share and public scan data it knows; verify before quoting.
Description
Apache Karaf's shell/SSH command security is enforced by per-scope ACL configuration files (etc/org.apache.karaf.command.acl. .cfg). SecuredSessionFactoryImpl.checkSecurity() resolves the roles required for an invocation and, when no ACL rule matches the command, fails open: ACLConfigurationParser.Specificity.NO_MATCH sets passCheck = true. The safety valve for this, karaf.secured.command.compulsory.roles, ships commented out in etc/system.properties, so an unmatched command is allowed for any authenticated user. The shipped org.apache.karaf.command.acl.config ACL (assemblies/features/standard/src/main/feature/feature.xml, mirrored into instance/.../etc/org.apache.karaf.command.acl.config.cfg) has no install entry. It restricts delete to admin, restricts edit/property-*/update on the jmx.acl.*, org.apache.karaf.command.acl.* and org.apache.karaf.service.acl.* PIDs to admin, and allows manager for everything else, but config:install was simply unmatched, and therefore allowed for any authenticated user, including one holding only the viewer role. config:install fetches url and writes it into ${karaf.etc} as finalname. It calls PathUtils.checkWithin() to block .. traversal outside karaf.etc, but that folder holds every security-relevant file Karaf ships: users.properties, keys.properties, host.key, and all org.apache.karaf.*.acl.* files, including the very ACL file that (mis)governs this command. With -o/--override, an existing file is overwritten with attacker-controlled bytes fetched from an arbitrary URL. Because felix.fileinstall.dir = ${karaf.etc} (etc/config.properties), Felix FileInstall also watches and reloads any .cfg file dropped there, closing the loop without requiring a restart. By contrast, bundle:install, feature:install and kar:install are all admin-only in their own ACLs, and config:delete is admin in this same ACL, config:install was the outlier. MitigationAdd install = admin in etc/org.apache.karaf.command.acl.config.cfg (create the file is absent), and/or set karaf.secured.command.compulsory.roles=admin in etc/system.properties (and restart) to make unmatched commands fail closed by default.