In Dovecot before 184.108.40.206 and 2.3.x before 220.127.116.11, a local attacker can cause a buffer overflow in the indexer-worker process, which can be used to elevate to root. This occurs because of missing checks in the fts and pop3-uidl components.
Created dovecot tracking bugs for this issue:
Affects: fedora-all [bug 1696156]
Dovecot during its normal operation creates index files which makes reading of the email easier. Each inbox has a set of index files which are created from the emails in the inbox. When index files are disabled they are stored in memory. Only local user who owns the inbox for the particular account has access to the index files.
In order to trigger the security flaw, the attacker needs to have local access to the dovecot.index.log file and must be able to manipulate it. Later when dovecot indexer-worker tries to parse the file, it could result in a stack-based buffer overflow and a crash. Code execution is quite possible here specially in the older versions where security technology like StackGuard etc are not enabled.
This issue has been addressed in the following products:
Red Hat Enterprise Linux 7
Via RHSA-2020:1062 https://access.redhat.com/errata/RHSA-2020:1062
This bug is now closed. Further updates for individual products will be reflected on the CVE page(s):