Details for this vulnerability have not been published by NIST at this point. Descriptions from software vendor advisories for this issue are provided below.
Aki Tuomi reports:
IMAP and ManageSieve protocol parsers do not properly handle NUL byte
when scanning data in quoted strings, leading to out of bounds heap
This vulnerability allows for out-of-bounds writes to objects stored on
the heap up to 8096 bytes in pre-login phase, and 65536 bytes post-login
phase, allowing sufficiently skilled attacker to perform complicated
attacks that can lead to leaking private information or remote code
execution. Abuse of this bug is very difficult to observe, as it does
not necessarily cause a crash. Attempts to abuse this bug are not
directly evident from logs.