Vulnerabilities > CVE-2021-20230 - Unspecified vulnerability in Stunnel

CVSS 7.5 - HIGH

Attack vector

NETWORK

Attack complexity

LOW

Privileges required

NONE

Confidentiality impact

HIGH

Integrity impact

NONE

Availability impact

NONE

network

low complexity

stunnel

NVD

Published: 2021-02-23

Updated: 2024-11-21

Summary

A flaw was found in stunnel before 5.57, where it improperly validates client certificates when it is configured to use both redirect and verifyChain options. This flaw allows an attacker with a certificate signed by a Certificate Authority, which is not the one accepted by the stunnel server, to access the tunneled service instead of being redirected to the address specified in the redirect option. The highest threat from this vulnerability is to confidentiality.

Vulnerable Configurations

Part	Description	Count
Application	Stunnel Stunnel Stunnel 0.1 Stunnel Stunnel 1.0 Stunnel Stunnel 1.1 Stunnel Stunnel 1.2 Stunnel Stunnel 1.3 Stunnel Stunnel 1.4 Stunnel Stunnel 1.5 Stunnel Stunnel 1.6 Stunnel Stunnel 2.0 Stunnel Stunnel 2.1 Stunnel Stunnel 3.0 Stunnel Stunnel 3.1 Stunnel Stunnel 3.2 Stunnel Stunnel 3.3 Stunnel Stunnel 3.4A Stunnel Stunnel 3.5 Stunnel Stunnel 3.6 Stunnel Stunnel 3.7 Stunnel Stunnel 3.8 Stunnel Stunnel 3.9 Stunnel Stunnel 3.10 Stunnel Stunnel 3.11 Stunnel Stunnel 3.12 Stunnel Stunnel 3.13 Stunnel Stunnel 3.14 Stunnel Stunnel 3.15 Stunnel Stunnel 3.16 Stunnel Stunnel 3.17 Stunnel Stunnel 3.18 Stunnel Stunnel 3.19 Stunnel Stunnel 3.20 Stunnel Stunnel 3.21 Stunnel Stunnel 3.21A Stunnel Stunnel 3.21B Stunnel Stunnel 3.21C Stunnel Stunnel 3.22 Stunnel Stunnel 3.23 Stunnel Stunnel 3.24 Stunnel Stunnel 3.25 Stunnel Stunnel 3.26 Stunnel Stunnel 4.0 Stunnel Stunnel 4.01 Stunnel Stunnel 4.02 Stunnel Stunnel 4.03 Stunnel Stunnel 4.04 Stunnel Stunnel 4.05 Stunnel Stunnel 4.06 Stunnel Stunnel 4.07 Stunnel Stunnel 4.08 Stunnel Stunnel 4.09 Stunnel Stunnel 4.10 Stunnel Stunnel 4.11 Stunnel Stunnel 4.12 Stunnel Stunnel 4.13 Stunnel Stunnel 4.14 Stunnel Stunnel 4.15 Stunnel Stunnel 4.16 Stunnel Stunnel 4.17 Stunnel Stunnel 4.18 Stunnel Stunnel 4.19 Stunnel Stunnel 4.20 Stunnel Stunnel 4.21 Stunnel Stunnel 4.22 Stunnel Stunnel 4.23 Stunnel Stunnel 4.24 Stunnel Stunnel 4.25 Stunnel Stunnel 4.26 Stunnel Stunnel 4.27 Stunnel Stunnel 4.28 Stunnel Stunnel 4.29 Stunnel Stunnel 4.30 Stunnel Stunnel 4.31 Stunnel Stunnel 4.32 Stunnel Stunnel 4.33 Stunnel Stunnel 4.34 Stunnel Stunnel 4.35 Stunnel Stunnel 4.36 Stunnel Stunnel 4.37 Stunnel Stunnel 4.38 Stunnel Stunnel 4.39 Stunnel Stunnel 4.40 Stunnel Stunnel 4.41 Stunnel Stunnel 4.42 Stunnel Stunnel 4.43 Stunnel Stunnel 4.44 Stunnel Stunnel 4.45 Stunnel Stunnel 4.46 Stunnel Stunnel 4.47 Stunnel Stunnel 4.48 Stunnel Stunnel 4.49 Stunnel Stunnel 4.50 Stunnel Stunnel 4.51 Stunnel Stunnel 4.52 Stunnel Stunnel 4.53 Stunnel Stunnel 4.54 Stunnel Stunnel 4.55 Stunnel Stunnel 4.56 Stunnel Stunnel 4.57 Stunnel Stunnel 5.00 Stunnel Stunnel 5.01 Stunnel Stunnel 5.02 Stunnel Stunnel 5.03 Stunnel Stunnel 5.04 Stunnel Stunnel 5.05 Stunnel Stunnel 5.06 Stunnel Stunnel 5.07 Stunnel Stunnel 5.08 Stunnel Stunnel 5.09 Stunnel Stunnel 5.10 Stunnel Stunnel 5.11 Stunnel Stunnel 5.12 Stunnel Stunnel 5.13 Stunnel Stunnel 5.14 Stunnel Stunnel 5.15 Stunnel Stunnel 5.16 Stunnel Stunnel 5.17 Stunnel Stunnel 5.18 Stunnel Stunnel 5.19 Stunnel Stunnel 5.20 Stunnel Stunnel 5.21 Stunnel Stunnel 5.22 Stunnel Stunnel 5.23 Stunnel Stunnel 5.24 Stunnel Stunnel 5.25 Stunnel Stunnel 5.26 Stunnel Stunnel 5.27 Stunnel Stunnel 5.28 Stunnel Stunnel 5.29 Stunnel Stunnel 5.30 Stunnel Stunnel 5.31 Stunnel Stunnel 5.32 Stunnel Stunnel 5.33 Stunnel Stunnel 5.34 Stunnel Stunnel 5.35 Stunnel Stunnel 5.36 Stunnel Stunnel 5.37 Stunnel Stunnel 5.38 Stunnel Stunnel 5.39 Stunnel Stunnel 5.40 Stunnel Stunnel 5.41 Stunnel Stunnel 5.42 Stunnel Stunnel 5.43 Stunnel Stunnel 5.44 Stunnel Stunnel 5.45 Stunnel Stunnel 5.46 Stunnel Stunnel 5.47 Stunnel Stunnel 5.48 Stunnel Stunnel 5.49 Stunnel Stunnel 5.50 Stunnel Stunnel 5.51 Stunnel Stunnel 5.52 Stunnel Stunnel 5.53 Stunnel Stunnel 5.54	164

Summary

Vulnerable Configurations

References