Vulnerability in Stunnel
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.
Vulnerability class: Improper Certificate Validation
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N.
EPSS exploit prediction
EPSS: 0.012 (66.6th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 67th percentile — 66.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.012 · newest: 0.012 · change: 0.000
Affected products
- Stunnel
- Stunnel — versions stunnel 5.57
Weakness classification (CWE)
References
- bugzilla.redhat.com/show_bug.cgi (Third Party Advisory, Issue Tracking)
- github.com/mtrojnar/stunnel/commit/ebad9ddc4efb2635f37174c9d800d06206f1edf9 (Patch, Third Party Advisory)
- security.gentoo.org/glsa/202105-02 (vendor-advisory, Third Party Advisory)
Frequently asked questions
- What is CVE-2021-20230?
- CVE-2021-20230 is a high-severity vulnerability in Stunnel, classified under Improper Certificate Validation. CVSS score: 7.5/10. Published 2021-02-23.
- How severe is CVE-2021-20230?
- High severity. CVSS v3 base score is 7.5 out of 10.