A number of flaws were reported [1] in eCryptfs that could allow a user to mount or unmount arbitrary locations, and possibly disclose confidential information:

Vasiliy Kulikov of Openwall and Dan Rosenberg discovered that eCryptfs incorrectly validated permissions on the requested mountpoint. A local attacker could use this flaw to mount to arbitrary locations, leading to privilege escalation. (CVE-2011-1831)

Vasiliy Kulikov of Openwall and Dan Rosenberg discovered that eCryptfs incorrectly validated permissions on the requested mountpoint. A local attacker could use this flaw to unmount to arbitrary locations, leading to a denial of service. (CVE-2011-1832)

Vasiliy Kulikov of Openwall and Dan Rosenberg discovered that eCryptfs incorrectly validated permissions on the requested source directory. A local attacker could use this flaw to mount an arbitrary directory, possibly leading to information disclosure. Note that this flaw also requires a fix in the kernel to be complete. (CVE-2011-1833)

Dan Rosenberg and Marc Deslauriers discovered that eCryptfs incorrectly handled modifications to the mtab file when an error occurs. A local attacker could use this flaw to corrupt the mtab file, and possibly unmount arbitrary locations, leading to a denial of service. (CVE-2011-1834)

Marc Deslauriers discovered that eCryptfs incorrectly handled keys when setting up an encrypted private directory. A local attacker could use this flaw to manipulate keys during creation of a new user. (CVE-2011-1835)

Marc Deslauriers discovered that eCryptfs incorrectly handled permissions during recovery. A local attacker could use this flaw to possibly access another user's data during the recovery process. (CVE-2011-1836)

Vasiliy Kulikov of Openwall discovered that eCryptfs incorrectly handled lock counters. A local attacker could use this flaw to possibly overwrite arbitrary files. (CVE-2011-1837)

[1] https://launchpad.net/bugs/732628