It was found that glibc's utility, responsible for editing of system's mtab table, improperly sanitized user supplied mount point names containing certain special character. Local attacker could use this flaw to add arbitrary mount points (corrupt system's "/etc/mtab" file) or, potentially, set unauthorized mount options. Other attacks are also possible.

Issue severity note: ------------------- The /etc/mtab file handles mounted devices and is automatically updated by the mount command (more precisely by the dedicated "mount" tool for relevant filesystem). Unprivileged user to be able to run such a tool (and modify content of /etc/mtab), this tool needs to be suid root enabled. The dedicated "mount" tools, as shipped with Red Hat Enterprise Linux (mount.cifs, mount.fuse, fusermount, mount.nfs, mount.nfs4) does NOT allow unprivileged user to use them (without prior grant of additional privileges from the privileged user) for editing of system's /etc/mtab file, which mitigates impact of this flaw.