How severe is CVE-2017-12166?

CVE-2017-12166 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2017-12166 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 4% (88th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2017-12166?

CVE-2017-12166 primarily affects Openvpn. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2017-12166?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2017-12166 published?

CVE-2017-12166 was published on 2017-10-04 and last updated on 2026-06-17.

CVE-2017-12166

CVE-2017-12166 is a critical-severity vulnerability in Openvpn with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-787.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 6.8
EPSS exploit prediction: 4% (88th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-787
Affected product: Openvpn
Published: 2017-10-04
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is 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.
How severe is CVE-2017-12166?: CVE-2017-12166 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2017-12166 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 4% (88th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2017-12166?: CVE-2017-12166 primarily affects Openvpn. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2017-12166?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2017-12166 published?: CVE-2017-12166 was published on 2017-10-04 and last updated on 2026-06-17.

References

Affected products (2)

cpe:2.3:a:openvpn:openvpn:*:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*

More vulnerabilities in Openvpn

CVE-2024-27903 — Critical (CVSS 9.8): OpenVPN plug-ins on Windows with OpenVPN 2.6.9 and earlier could be loaded from any directory, which allows an attacker…
CVE-2023-46850 — Critical (CVSS 9.8): Use after free in OpenVPN version 2.6.0 to 2.6.6 may lead to undefined behavoir, leaking memory buffers or remote…
CVE-2022-0547 — Critical (CVSS 9.8): OpenVPN 2.1 until v2.4.12 and v2.5.6 may enable authentication bypass in external authentication plug-ins when more…
CVE-2025-12106 — Critical (CVSS 9.1): Insufficient argument validation in OpenVPN 2.7_alpha1 through 2.7_rc1 allows an attacker to trigger a heap buffer…
CVE-2024-5594 — Critical (CVSS 9.1): OpenVPN before 2.6.11 does not santize PUSH_REPLY messages properly which an attacker controlling the server can use to…
CVE-2018-7544 — Critical (CVSS 9.1): A cross-protocol scripting issue was discovered in the management interface in OpenVPN through 2.4.5. When this…

All CVEs affecting Openvpn →

Other CWE-787 (Out-of-bounds Write) vulnerabilities

CVE-2026-42369 — Critical (CVSS 10.0): GV-VMS V20 is a Video Monitoring Software used to gather the feeds of many surveillance cameras and manage other…
CVE-2026-4746 — Critical (CVSS 10.0): Out-of-bounds Write vulnerability in timeplus-io proton (base/poco/Foundation/src‎ modules). This vulnerability is…
CVE-2025-43300 — Critical (CVSS 10.0): An out-of-bounds write issue was addressed with improved bounds checking. This issue is fixed in iOS 15.8.5 and iPadOS…
CVE-2025-24201 — Critical (CVSS 10.0): An out-of-bounds write issue was addressed with improved checks to prevent unauthorized actions. This issue is fixed in…
CVE-2024-42479 — Critical (CVSS 10.0): llama.cpp provides LLM inference in C/C++. The unsafe `data` pointer member in the `rpc_tensor` structure can cause…
CVE-2024-39791 — Critical (CVSS 10.0): Stack-based buffer overflow vulnerabilities affecting Vonets industrial wifi bridge relays and wifi bridge…

Browse all CWE-787 (Out-of-bounds Write) vulnerabilities →