CVE-2021-20230
7.5
HIGH
CVSS 3.1
EPSS 0.21%
Description
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.
How to fix CVE-2021-20230
To remediate CVE-2021-20230, upgrade the affected package to a fixed version below.
- —upgrade to 3:5.56+dfsg-8 or later
Is CVE-2021-20230 being exploited?
Low — EPSS is 0.2%, meaning exploitation activity has not been observed at scale.
Affected packages (1)
- from 0, < 3:5.56+dfsg-8
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | HIGH7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N |