In rfb/CSecurityTLS.cxx and rfb/CSecurityTLS.java in TigerVNC before 1.11.0, viewers mishandle TLS certificate exceptions. They store the certificates as authorities, meaning that the owner of a certificate could impersonate any server after a client had added an exception.
Source: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-26117
Reference (s):
- https://bugzilla.opensuse.org/show_bug.cgi?id=1176733
- https://github.com/TigerVNC/tigervnc/commit/20dea801e747318525a5859fe4f37c52b05310cb
- https://github.com/TigerVNC/tigervnc/commit/7399eab79a4365434d26494fa1628ce1eb91562b
- https://github.com/TigerVNC/tigervnc/commit/b30f10c681ec87720cff85d490f67098568a9cba
- https://github.com/TigerVNC/tigervnc/commit/f029745f63ac7d22fb91639b2cb5b3ab56134d6e