DEBIAN-CVE-2021-20230

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Source
https://security-tracker.debian.org/tracker/CVE-2021-20230
Import Source
https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2021-20230.json
JSON Data
https://api.osv.dev/v1/vulns/DEBIAN-CVE-2021-20230
Upstream
Published
2021-02-23T17:15:13.753Z
Modified
2025-11-19T02:02:40.575317Z
Severity
  • 7.5 (High) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N CVSS Calculator
Summary
[none]
Details

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.

References

Affected packages

Debian:11 / stunnel4

Package

Name
stunnel4
Purl
pkg:deb/debian/stunnel4?arch=source

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected
Fixed
3:5.56+dfsg-8

Ecosystem specific 

{
    "urgency": "not yet assigned"
}

Database specific

source 
"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2021-20230.json"

Debian:12 / stunnel4

Package

Name
stunnel4
Purl
pkg:deb/debian/stunnel4?arch=source

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected
Fixed
3:5.56+dfsg-8

Ecosystem specific 

{
    "urgency": "not yet assigned"
}

Database specific

source 
"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2021-20230.json"

Debian:13 / stunnel4

Package

Name
stunnel4
Purl
pkg:deb/debian/stunnel4?arch=source

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected
Fixed
3:5.56+dfsg-8

Ecosystem specific 

{
    "urgency": "not yet assigned"
}

Database specific

source 
"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2021-20230.json"

Debian:14 / stunnel4

Package

Name
stunnel4
Purl
pkg:deb/debian/stunnel4?arch=source

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected
Fixed
3:5.56+dfsg-8

Ecosystem specific 

{
    "urgency": "not yet assigned"
}

Database specific

source 
"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2021-20230.json"