Quoting Ubuntu advisory:
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. This issue only applied to Ubuntu 11.04. (CVE-2011-1836)
Patch is attached in the bug that track other issues from the advisory:
As was noted in bug #729465, comment #8:
CVE-2011-1836 only affects Fedora; ecryptfs-recover-private does not exist in
ecryptfs-utils-82 (which is what is shipped with Red Hat Enterprise Linux 6).
Not vulnerable. This issue did not affect the versions of ecryptfs-utils as
shipped with Red Hat Enterprise Linux 5 or 6.