Improper Certificate Validation Affecting stunnel package, versions <0:5.56-5.el8_3


Severity

Recommended
0.0
high
0
10

Based on Red Hat Enterprise Linux security rating.

Threat Intelligence

EPSS
0.16% (53rd percentile)

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  • Snyk IDSNYK-RHEL8-STUNNEL-3956607
  • published26 Jul 2021
  • disclosed11 Oct 2020

Introduced: 11 Oct 2020

CVE-2021-20230  (opens in a new tab)
CWE-295  (opens in a new tab)

How to fix?

Upgrade RHEL:8 stunnel to version 0:5.56-5.el8_3 or higher.
This issue was patched in RHSA-2021:0618.

NVD Description

Note: Versions mentioned in the description apply only to the upstream stunnel package and not the stunnel package as distributed by RHEL. See How to fix? for RHEL:8 relevant fixed versions and status.

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.

CVSS Scores

version 3.1