What is CVE-2017-12166?

CVE-2017-12166 is a critical-severity vulnerability in Openvpn, classified under Out-of-bounds Write. CVSS score: 9.8/10. Published 2017-10-04.

How severe is CVE-2017-12166?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Buffer overflow in Openvpn

CVE-2017-12166

OpenVPN versions before 2.3.3 and 2.4.x before 2.4.4 are vulnerable to a buffer overflow vulnerability when key-method 1 is used, possibly resulting in code execution.

Vulnerability class: Buffer Overflow

Published 2017-10-04 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.036 (89.4th percentile), scored 2026-10-20.

Low probability of exploitation in the next 30 days, but still tracked. 89th percentile — 89.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.036 · newest: 0.036 · change: 0.000

Affected products

Openvpn
Debian Linux — versions 9.0

Weakness classification (CWE)

CWE-787 — Out-of-bounds Write

References

community.openvpn.net/openvpn/wiki/CVE-2017-12166 (Patch, Vendor Advisory)
www.securityfocus.com/bid/101153 (URL Repurposed, VDB Entry, Third Party Advisory, vdb-entry)
www.securitytracker.com/id/1039470 (URL Repurposed, VDB Entry, Third Party Advisory, vdb-entry)
lists.debian.org/debian-lts-announce/2022/05/msg00002.html (mailing-list, Mailing List, Third Party Advisory)

Frequently asked questions

What is CVE-2017-12166?: CVE-2017-12166 is a critical-severity vulnerability in Openvpn, classified under Out-of-bounds Write. CVSS score: 9.8/10. Published 2017-10-04.
How severe is CVE-2017-12166?: Critical severity. CVSS v3 base score is 9.8 out of 10.