CVE-2020-26117

HIGHEPSS 86th pctl

8.1

CVSS v3

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.

CWE-295Improper Certificate Validation

How to fix

Remediation Available

tigervncDebian

Fixed in:1.10.1+dfsg-9CVE-2020-26117

tigervncUbuntu

Fixed in:1.10.1+dfsg-3ubuntu0.1+esm2USN-5965-1

tigervnc-commonUbuntu

Fixed in:1.10.1+dfsg-3ubuntu0.1+esm2USN-5965-1

tigervnc-scraping-serverUbuntu

Fixed in:1.10.1+dfsg-3ubuntu0.1+esm2USN-5965-1

tigervnc-standalone-serverUbuntu

Fixed in:1.10.1+dfsg-3ubuntu0.1+esm2USN-5965-1

TigerVNCWindows application

Affected:1.11.0Fixed in:1.11.0TigerVNC project

TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionRequired

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityNone

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

Exploit Intelligence

3.06%probability of exploitation in 30 days

86thpercentile

Elevated risk: more likely to be exploited than 86% of all known CVEs.

References

Patch4

Third-Party Advisory5

Related Vulnerabilities

Other CWE-295 (Improper Certificate Validation) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2015-4000	Low	3.7	100%	-	Fix
CVE-2020-0601	High	8.1	89%	KEV	Fix
CVE-2009-3555	Critical	9.8	87%	-	Fix
CVE-2022-26923	High	8.8	83%	KEV	Fix
CVE-2023-27823	Critical	9.8	53%	-	-
CVE-2022-42979	High	8.8	24%	-	-

Common questions

How do I fix CVE-2020-26117?

Published advisories record a fix for 6 affected products. The "How to fix" section on this page lists the fixed version and source advisory for each one, so apply the entry matching what you actually run.

Is CVE-2020-26117 being actively exploited?

Not that we know of. CVE-2020-26117 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 3.1% is the estimated probability that it will be exploited in the next 30 days. That is higher than 86% of all scored CVEs.

How severe is CVE-2020-26117?

CVE-2020-26117 has a CVSS v3 base score of 8.1, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.

What does CVE-2020-26117 affect?

Published advisories record a fix for tigervnc (Debian), tigervnc (Ubuntu), tigervnc-common (Ubuntu), tigervnc-scraping-server (Ubuntu), and 2 more. Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2024-11-21.