Vulnerability Details : CVE-2021-20230
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.
Exploit prediction scoring system (EPSS) score for CVE-2021-20230
Probability of exploitation activity in the next 30 days: 0.12%
Percentile, the proportion of vulnerabilities that are scored at or less: ~ 45 % EPSS Score History EPSS FAQ
CVSS scores for CVE-2021-20230
| Base Score | Base Severity | CVSS Vector | Exploitability Score | Impact Score | Score Source |
|---|---|---|---|---|---|
|
5.0
|
MEDIUM | AV:N/AC:L/Au:N/C:P/I:N/A:N |
10.0
|
2.9
|
NIST |
|
7.5
|
HIGH | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N |
3.9
|
3.6
|
NIST |
CWE ids for CVE-2021-20230
-
The product does not validate, or incorrectly validates, a certificate.Assigned by: secalert@redhat.com (Primary)
References for CVE-2021-20230
-
https://security.gentoo.org/glsa/202105-02
stunnel: Improper certificate validation (GLSA 202105-02) — Gentoo securityThird Party Advisory
-
https://github.com/mtrojnar/stunnel/commit/ebad9ddc4efb2635f37174c9d800d06206f1edf9
stunnel-5.57 · mtrojnar/stunnel@ebad9dd · GitHubPatch;Third Party Advisory
-
https://bugzilla.redhat.com/show_bug.cgi?id=1925226
1925226 – (CVE-2021-20230) CVE-2021-20230 stunnel: client certificate not correctly verified when redirect and verifyChain options are usedIssue Tracking;Third Party Advisory
Products affected by CVE-2021-20230
- cpe:2.3:a:stunnel:stunnel:*:*:*:*:*:*:*:*