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Vulnerability record · CVE-2020-26117 · published 27 September 2020

CVE-2020-26117: Tigervnc improper certificate validation vulnerability

Tigervnc · Tigervnc

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.

8.1 CVSS 3.1 High EPSS 3.1% · top 12.9% CWE-295 · Improper certificate validation
8.1CVSS 3.1 base score, v2 5.8
3.1%EPSS exploitation probability, 30 days
NoNot in CISA KEV
3Affected product versions listed by NVD
18References
17 Jun 2026Last modified by NVD

Description

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.

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N

Affected products

3 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
http://lists.opensuse.org/opensuse-security-announce/2020-10/msg00025.html Broken LinkMailing ListThird Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2020-11/msg00024.html Broken LinkMailing ListThird Party Advisory
https://bugzilla.opensuse.org/show_bug.cgi?id=1176733 Issue TrackingThird Party Advisory
https://github.com/TigerVNC/tigervnc/commit/20dea801e747318525a5859fe4f37c52b05310cb PatchThird Party Advisory
https://github.com/TigerVNC/tigervnc/commit/7399eab79a4365434d26494fa1628ce1eb91562b PatchThird Party Advisory
https://github.com/TigerVNC/tigervnc/commit/b30f10c681ec87720cff85d490f67098568a9cba PatchThird Party Advisory
https://github.com/TigerVNC/tigervnc/commit/f029745f63ac7d22fb91639b2cb5b3ab56134d6e PatchThird Party Advisory
https://github.com/TigerVNC/tigervnc/releases/tag/v1.11.0 Release NotesThird Party Advisory
https://lists.debian.org/debian-lts-announce/2020/10/msg00007.html Mailing ListThird Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2020-10/msg00025.html Broken LinkMailing ListThird Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2020-11/msg00024.html Broken LinkMailing ListThird Party Advisory
https://bugzilla.opensuse.org/show_bug.cgi?id=1176733 Issue TrackingThird Party Advisory
https://github.com/TigerVNC/tigervnc/commit/20dea801e747318525a5859fe4f37c52b05310cb PatchThird Party Advisory
https://github.com/TigerVNC/tigervnc/commit/7399eab79a4365434d26494fa1628ce1eb91562b PatchThird Party Advisory
https://github.com/TigerVNC/tigervnc/commit/b30f10c681ec87720cff85d490f67098568a9cba PatchThird Party Advisory
https://github.com/TigerVNC/tigervnc/commit/f029745f63ac7d22fb91639b2cb5b3ab56134d6e PatchThird Party Advisory
https://github.com/TigerVNC/tigervnc/releases/tag/v1.11.0 Release NotesThird Party Advisory
https://lists.debian.org/debian-lts-announce/2020/10/msg00007.html Mailing ListThird Party Advisory

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Source: NIST National Vulnerability Database (record CVE-2020-26117), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.