Improper Certificate Validation in TigerVNC - CVE-2020-26117
Published: September 27, 2020 / Updated: October 13, 2020
Vulnerability identifier: #VU47533
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2020-26117
CWE-ID: CWE-295
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: tigervnc.org
Affected software:
TigerVNC
TigerVNC
Detailed vulnerability description
The vulnerability allows a remote attacker to perform a MitM attack.
The vulnerability exists due to improper TLS certificate validation in rfb/CSecurityTLS.cxx and rfb/CSecurityTLS.java in TigerVNC. Any previously accepted certificate will be considered trusted, meaning that the owner of a certificate could impersonate any server after a client had added an exception.
How to mitigate CVE-2020-26117
Install updates from vendor's website.
Sources
- 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
- https://github.com/TigerVNC/tigervnc/releases/tag/v1.11.0
- https://lists.debian.org/debian-lts-announce/2020/10/msg00007.html