CVE-2020-26117
Description
From CVE.org
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.
Mitigation
This flaw can be mitigated by not making certificate exceptions in the affected versions of tigervnc, and therefore they will not be stored as authorities.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 8.1 | 8.1 | N/A |
| Attack Vector | Network | Network | N/A |
| Attack Complexity | Low | Low | N/A |
| Privileges Required | None | None | N/A |
| User Interaction | Required | Required | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | High | High | N/A |
| Integrity Impact | High | High | N/A |
| Availability Impact | None | None | N/A |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
NVD: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
Red Hat CVSS v3 Score Explanation
UI:R because a user needs to add an exception for a certificate for this vulnerability to be exploitable. C:H because if an attacker impersonates a server, this could cause a client to divulge sensitive information to a malicious server.
Understanding the Weakness (CWE)
Non-Repudiation
Technical Impact: Hide Activities
Exploitation of this flaw can lead to the trust of data that may have originated with a spoofed source.
Integrity,Confidentiality,Availability,Access Control
Technical Impact: Gain Privileges or Assume Identity; Execute Unauthorized Code or Commands
Data, requests, or actions taken by the attacking entity can be carried out as a spoofed benign entity.
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