Updated mm packages are now available for Red Hat Linux 7, 7.1, 7.2, and 7.3. These updates address possible vulnerabilities in how the MM library opens temporary files.
The MM library provides an abstraction layer which allows related processes to share data easily. On systems where shared memory or other inter-process communication mechanisms are not available, the MM library emulates them using temporary files. MM is used in Red Hat Linux to providing shared memory pools to Apache modules. Versions of MM up to and including 1.1.3 open temporary files in an unsafe manner, allowing a malicious local user to cause an application which uses MM to overwrite any file to which it has write access. All users are advised to upgrade to these errata packages, which contain a patched version of MM that is not vulnerable to this issue. Thanks to Marcus Meissner for providing a patch for this issue.