CVE-2021-20230

Summary

CVECVE-2021-20230
StatePUBLIC
Assigner[email protected]
Source PriorityCVE Program / NVD first with legacy fallback
Published2021-02-23 17:15:00 UTC
Updated2022-06-01 18:05:00 UTC
DescriptionA 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.

Risk And Classification

Problem Types: CWE-295

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Stunnel Stunnel All All All All
Application Stunnel Stunnel All All All All

References

ReferenceSourceLinkTags
stunnel: Improper certificate validation (GLSA 202105-02) — Gentoo security GENTOO security.gentoo.org
1925226 – (CVE-2021-20230) CVE-2021-20230 stunnel: client certificate not correctly verified when redirect and verifyChain options are used MISC bugzilla.redhat.com Issue Tracking, Third Party Advisory
stunnel-5.57 · mtrojnar/stunnel@ebad9dd · GitHub MISC github.com Patch, Third Party Advisory
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Legacy QID Mappings

  • 174790 SUSE Enterprise Linux Security update for stunnel (SUSE-SU-2021:0772-1)
  • 174973 SUSE Enterprise Linux Security Update for stunnel (SUSE-SU-2021:1465-1)
  • 179817 Debian Security Update for stunnel4 (CVE-2021-20230)
  • 296059 Oracle Solaris 11.4 Support Repository Update (SRU) 36.0.1.101.2 Missing (CPUJUL2021)
  • 376189 Stunnel Improper Certificate Validation Vulnerability
  • 377138 Alibaba Cloud Linux Security Update for stunnel (ALINUX3-SA-2021:0011)
  • 670335 EulerOS Security Update for stunnel (EulerOS-SA-2021-1889)
  • 710113 Gentoo Linux stunnel Improper certificate validation vulnerability (GLSA 202105-02)
  • 750322 OpenSUSE Security Update for stunnel (openSUSE-SU-2021:0409-1)
  • 901597 Common Base Linux Mariner (CBL-Mariner) Security Update for stunnel (7375)
  • 907275 Common Base Linux Mariner (CBL-Mariner) Security Update for stunnel (7375-1)
  • 940001 AlmaLinux Security Update for stunnel (ALSA-2021:0618)
  • 960686 Rocky Linux Security Update for stunnel (RLSA-2021:0618)
© CVE.report 2026 |

Use of this information constitutes acceptance for use in an AS IS condition. There are NO warranties, implied or otherwise, with regard to this information or its use. Any use of this information is at the user's risk. It is the responsibility of user to evaluate the accuracy, completeness or usefulness of any information, opinion, advice or other content. EACH USER WILL BE SOLELY RESPONSIBLE FOR ANY consequences of his or her direct or indirect use of this web site. ALL WARRANTIES OF ANY KIND ARE EXPRESSLY DISCLAIMED. This site will NOT BE LIABLE FOR ANY DIRECT, INDIRECT or any other kind of loss.

CVE, CWE, and OVAL are registred trademarks of The MITRE Corporation and the authoritative source of CVE content is MITRE's CVE web site. This site includes MITRE data granted under the following license.

CVE.report and Source URL Uptime Status status.cve.report