An issue was discovered in Cyrus IMAP before 2.5.15, 3.0.x before 3.0.13, and 3.1.x through 3.1.8. If sieve script uploading is allowed (3.x) or certain non-default sieve options are enabled (2.x), a user with a mail account on the service can use a sieve script containing a fileinto directive to create any mailbox with administrator privileges, because of folder mishandling in autosieve_createfolder() in imap/lmtp_sieve.c.
In Apache SpamAssassin before 3.4.3, a message can be crafted in a way to use excessive resources. Upgrading to SA 3.4.3 as soon as possible is the recommended fix but details will not be shared publicly.
In Apache SpamAssassin before 3.4.3, nefarious CF files can be configured to run system commands without any output or errors. With this, exploits can be injected in a number of scenarios. In addition to upgrading to SA 3.4.3, we recommend that users should only use update channels or 3rd party .cf files from trusted places.
A reflected XSS issue was discovered in DAViCal through 1.1.8. It echoes the action parameter without encoding. If a user visits an attacker-supplied link, the attacker can view all data the attacked user can view, as well as perform all actions in the name of the user. If the user is an administrator, the attacker can for example add a new admin user to gain full access to the application.
An issue was discovered in Xen through 4.12.x allowing x86 HVM/PVH guest OS users to cause a denial of service (guest OS crash) because VMX VMEntry checks mishandle a certain case. Please see XSA-260 for background on the MovSS shadow. Please see XSA-156 for background on the need for #DB interception. The VMX VMEntry checks do not like the exact combination of state which occurs when #DB in intercepted, Single Stepping is active, and blocked by STI/MovSS is active, despite this being a legitimate state to be in. The resulting VMEntry failure is fatal to the guest. HVM/PVH guest userspace code may be able to crash the guest, resulting in a guest Denial of Service. All versions of Xen are affected. Only systems supporting VMX hardware virtual extensions (Intel, Cyrix, or Zhaoxin CPUs) are affected. Arm and AMD systems are unaffected. Only HVM/PVH guests are affected. PV guests cannot leverage the vulnerability.