24th March 2020
Risk level: Low
CVSS v3 Base Score: 5.9 (AV:N/AC:H/PR:L/UI:R/S:U/C:H/I:L/A:L)
CWE: Improper Certificate Validation (CWE-295)
HackerOne report: 803734
A missing verification of the TLS host in Nextcloud Mail 1.1.3 allowed a man in the middle attack.
The error has been fixed.
It is recommended that the Nextcloud Mail app is upgraded to 1.1.4.
The Nextcloud team thanks the following people for their research and responsible disclosure of the above advisory: