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.
| Software | From | Fixed in |
|---|---|---|
| cyrus / imap | 3.1.0 | 3.1.8 |
| cyrus / imap | 2.5.0 | 2.5.15 |
| cyrus / imap | 3.0.0 | 3.0.13 |
| debian / debian_linux | 9.0 | 9.0.x |
| debian / debian_linux | 10.0 | 10.0.x |
| fedoraproject / fedora | 30 | 30.x |
| fedoraproject / fedora | 31 | 31.x |
| canonical / ubuntu_linux | 18.04 | 18.04.x |