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Openvpn CVE-2025-12106

| EUVDEUVD-2025-199988 CRITICAL
Buffer Over-read (CWE-126)
2025-12-01 security@openvpn.net
Buffer Overflow Openvpn
Critical
Disputed · 9.1 Vendor: openvpn
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Vulnerability Assessment

Weakness
CWE
CWE-126
OWASP Top 10:2025
A06:2021 - Vulnerable and Outdated Components
ASVS 5.0
V15 - Secure Coding and Architecture Buffer over-read prevention
Impact

CVSS score of 9.1 (CRITICAL).
Act Now Prioritize within 24-48h. Why: CRITICAL severity.
Patch available 0.1% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 15, 2026

Insufficient argument validation in OpenVPN 2.7_alpha1 through 2.7_rc1 allows an attacker to trigger a heap buffer over-read when parsing IP addresses

Earlier versions of this analysis (1)
v1 Mar 15, 2026 - 13:34 CVSS 9.1

RemediationAI

Monitor vendor advisories for patches. Apply mitigations such as network segmentation, access restrictions, and monitoring.

Affected VersionsENISA

OpenVPN 2.7_alpha1 ≤2.7_rc1

Affected Packages

euvd openvpn no fix

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

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Technical ContextAI · show details

This vulnerability is classified as Buffer Over-read (CWE-126).

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  • Exploit and PoC references, threat intelligence from 22 sources
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Severity by source

Sources disagree (Medium–Critical)
Vendor (openvpn) PRIMARY 9.1 CRITICAL
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
Ubuntu MEDIUM
SUSE CRITICAL

vuln.today treats the vendor’s rating as authoritative. A higher third-party CVSS (e.g. CISA-ADP) is shown for transparency but does not drive the headline severity.

CVSS VectorVendor: openvpn

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
High

Lifecycle Timeline

2
Patch released
Mar 31, 2026 - 21:13 nvd
Patch available
CVE Published
Dec 01, 2025 - 13:16 nvd
CRITICAL 9.1

Executive ViewAI

Why It Matters

A critical vulnerability in OpenVPN versions 2.7_alpha1 through 2.7_rc1 allows remote attackers to trigger memory corruption through malformed IP address parsing, potentially leading to denial of service or code execution. Organizations running affected OpenVPN versions face immediate risk of service disruption and potential system compromise until remediation is deployed.

Business Impact: Severe
Compensating Controls

Implement network-level access controls restricting OpenVPN server connectivity to known trusted IP ranges; disable OpenVPN services on non-production systems pending patching; monitor OpenVPN processes for abnormal termination indicating exploitation attempts; consider immediate rollback to OpenVPN 2.6.x LTS release which is not affected by this vulnerability; implement rate limiting and connection throttling at network perimeter to mitigate DOS attempts exploiting this flaw.

Threat Intelligence Overview

EPSS Score
0.1%
Top 75% exploitable
Data Quality
5 sources
Confidence: Medium
EUVD NVD CVE.org EPSS Vendor VulDB

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity CRITICAL
CISA KEV No
Public POC No
EPSS 0.1%
Patch available Yes
Active threat No
Deciding rule
CRITICAL severity
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Out-of-Cycle
Exploitation· derived
None
System Exposure· derived
Open
Automatable· derived
Yes
Human Impact
Very High

Priority Score

46
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +46
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Buffer Overflow HIGH

A buffer overflow occurs when a program writes more data to a memory buffer than it was allocated to hold, causing the excess data to spill into adjacent memory regions.

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OpenVPN version 2.3.12 and newer is vulnerable to unauthenticated Denial of Service of server via received large control
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7.8 Feb 28

OpenVPN Connect 3.1.0.361 on Windows has Insecure Permissions for %PROGRAMDATA%\OpenVPN Connect\drivers\tap\amd64\win10,
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openvpnserv.exe (aka the interactive service helper) in OpenVPN 2.4.x before 2.4.6 allows a local attacker to cause a do
CVE-2017-5868 MEDIUM POC
6.1 May 26

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Comodo Dome Firewall 2.7.0 contains a reflected cross-site scripting vulnerability that allows attackers to inject malic
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Comodo Dome Firewall 2.7.0 contains multiple reflected cross-site scripting vulnerabilities in the openvpn_users endpoin
CVE-2017-12166 CRITICAL
9.8 Oct 04

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
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tap-windows6 driver version 9.26 and earlier does not properly check the size data of incomming write operations which a
CVE-2024-27903 CRITICAL
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OpenVPN plug-ins on Windows with OpenVPN 2.6.9 and earlier could be loaded from any directory, which allows an attacker

Same weakness CWE-126 – Buffer Over-read

View all
CVE-2017-7668 HIGH
7.5
CVE-2017-7679 CRITICAL POC
9.8
CVE-2021-34584 CRITICAL POC
9.1
CVE-2022-1987 HIGH POC
8.1
CVE-2022-1908 HIGH POC
8.1
CVE-2022-1907 HIGH POC
8.1
CVE-2022-2124 HIGH POC
7.8
CVE-2022-2175 HIGH POC
7.8

Same technique Buffer Overflow

View all
CVE-2017-7269 CRITICAL POC
9.8
CVE-2015-5119 CRITICAL POC
9.8
CVE-2015-3113 CRITICAL POC
9.8
CVE-2011-2462 CRITICAL POC
9.8
CVE-2020-0796 CRITICAL POC
10.0
CVE-2019-11043 CRITICAL POC
9.8
CVE-2009-0927 HIGH POC
8.8
CVE-2012-1889 HIGH POC
8.8

Vendor StatusVendor

Ubuntu

Priority: Medium
openvpn
Release Status Version
trusty not-affected code not present
xenial not-affected code not present
bionic not-affected code not present
focal not-affected code not present
jammy not-affected code not present
noble not-affected code not present
plucky not-affected code not present
questing not-affected code not present
upstream not-affected debian: Vulnerable code only in 2.7 upstream

Debian

openvpn
Release Status Fixed Version Urgency
bullseye fixed 2.5.1-3 -
bullseye (security) fixed 2.5.1-3+deb11u2 -
bookworm, bookworm (security) fixed 2.6.3-1+deb12u4 -
trixie (security), trixie fixed 2.6.14-1+deb13u1 -
forky, sid fixed 2.7.0-1 -
(unstable) not-affected - -

SUSE

Severity: Critical
Product Status
SUSE Linux Enterprise Desktop 15 SP7 Fixed
SUSE Linux Enterprise High Performance Computing 15 SP7 Fixed
SUSE Linux Enterprise Module for Basesystem 15 SP7 Fixed
SUSE Linux Enterprise Server 15 SP7 Fixed
SUSE Linux Enterprise Server for SAP Applications 15 SP7 Fixed

References

Advisories & patches
ADVISORY https://community.openvpn.net/Security%20Announcements/CVE-2025-12106 ADVISORY https://nvd.nist.gov/vuln/detail/CVE-2025-12106 ADVISORY https://vuldb.com/vuln/333850 REF https://www.mail-archive.com/openvpn-announce@lists.sourceforge.net/msg00152.html

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