An issue was discovered in Dovecot before 2.3.13. By using IMAP IDLE, an authenticated attacker can trigger unhibernation via attacker-controlled parameters, leading to access to other users’ email messages (and path disclosure).
packetstormsecurity.com/files/160842/Dovecot-2.3.11.3-Access-Bypass.html
seclists.org/fulldisclosure/2021/Jan/18
www.openwall.com/lists/oss-security/2021/01/04/4
doc.dovecot.org/configuration_manual/hibernation/
dovecot.org/pipermail/dovecot-news/2021-January/000450.html
dovecot.org/security
lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/GXDKFLOCUP7I4ELGQ2F4P5TGC6NXMYV7/
security.gentoo.org/glsa/202101-01
www.debian.org/security/2021/dsa-4825