A privilege escalation vulnerability (CVE-2017-15288) has been identified in the Scala compilation daemon.

We recommend upgrading to the latest versions of Scala (Scala 2.12.4, Scala 2.11.12 or Scala 2.10.7).

The compile daemon is started explicitly by the fsc command, or implicitly by executing a Scala source file as a script (e.g scala MyScript.scala). The Scala REPL, started by scala is not affected as it does not use the compilation daemon, nor is running a pre-compiled class using the scala command.

Impact

While the compile daemon is running, an attacker with local access to the machine can execute code as the user that started the compile daemon, and can write arbitrary class files to any location on the filesystem that the user has access to.

Affected Versions

• Scala 2.1.6-2.10.6; 2.11.0-2.11.11; 2.12.0-2.12.3

Mitigation

• Use scala -nocompdaemon MyScript.scala rather than scala MyScript.scala to disable the implicit startup and use of the daemon.
• Avoid explicitly starting fsc
• Upgrade to Scala 2.10.7 2.11.12, 2.12.4 or higher which restricts the sensitive file to be readable only by the owner. These releases also change the location of the sensitive file: it is written in the directory $HOME/.scalac.

Feedback

Please post any comments on Discourse. For details on the fix, the relevant PRs are: #6108 (2.11.12), #6120 (2.12.4), #6128 (2.10.7).