HighCVE-2026-40215

OpenVPN: Use After Free (CVE-2026-40215)

Published 08.06.2026Last modified 11.08.2026Sources: BSI, Debian LTS, SUSE, Debian, Ubuntu, CVE.org

What is affected, what to do

A race condition in OpenVPN 2.6.0 through 2.6.19 and 2.7_alpha1 through 2.7.1 allows remote attackers to potentially cause a server crash or leak heap memory via a use-after-free triggered during TLS session promotion.

Update openvpn to version 2.6.20, OpenVPN to version 2.7.2.

Affected: OpenVPN lte 2.6.0..2.6.19
OpenVPN lte 2.7_alpha1..2.7.1

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Metrics

7.4

Priority

XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.

Source: NVD, CVSS v3

7.4

CVSS v3

Severity High on the scale from 0 to 10.

Source: BSI, Debian LTS, SUSE, Debian, Ubuntu, CVE.org

0.4 %

EPSS score

Low — model estimates < 1% exploitation likelihood.

Source: FIRST EPSS, percentile 31.0

Show all metrics

Severity: High
Priority (0–325) The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first? Read in glossary: 63.32 Methodology
Exploit maturity An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack. Read in glossary: no public PoC known
XIEM Effective CVSS XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command. Read in glossary: 7.4 Methodology
CVSS v3 CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions. Read in glossary: 7.4
CVSS v4 CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions. Read in glossary: 6.1
EPSS score The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“. Read in glossary: 0.4 %; Low — model estimates < 1% exploitation likelihood.
EPSS percentile The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking. Read in glossary: 31.0; Elevated — this CVE ranks above at least 10% of all CVEs scored today.
KEV status The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching. Read in glossary: —
Published: 08.06.2026
CISA assessment (SSVC): Exploitation: none known · not automatable · Technical impact: partial; Source: CISA Vulnrichment, as of 16 June 2026
CWE CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect. Read in glossary: CWE-125, CWE-416

Detection rules

No NEOSEC detection rule is available for this vulnerability yet.

Classification under NIS2 and CRA

Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

NIS2 NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management. Read in glossary: High technical severity: assess and remediate the vulnerability in vulnerability handling under Art. 21(2)(e) NIS2 and document the decision.
CRA The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates. Read in glossary: From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.
ISO/IEC 27001 ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security. Read in glossary: Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

Description

Source: BSI WID Portal, BSI CSAF, Debian LTS Advisories, suse_csaf, Debian Security Advisories, Ubuntu Security Notices, NVD (NIST), CVE.org (MITRE), cvelistv5

Affected products

The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

Affected products
		Affected versions	Fixed in
OpenVPN	OpenVPN	`2.6.0 – ≤ 2.6.19` `2.7_alpha1 – ≤ 2.7.1`	— —
openvpn	openvpn	`2.6.0 – < 2.6.20` `2.7 – < 2.7.2`	`2.6.20` `2.7.2`
Open Source	OpenVPN	`< 2.7.2` `< 2.6.20`	`2.7.2` `2.6.20`

Vendors and products

Affected operating systems

Affected operating systems

Linux	debian	openvpn	`bookworm`
Linux	debian	openvpn	`bullseye`
Linux	debian	openvpn	`trixie`

Weakness classes (CWE)

CWE-125Out-of-bounds Read
Base
The product reads data past the end, or before the beginning, of the intended buffer.
Entry at MITRE CWE-125
CWE-416Use After Free
Variant
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.
Entry at MITRE CWE-416

References & sources

community.openvpn.netSecurity Announcements/CVE-2026-40215Vendor advisory
community.openvpn.netReleaseHistoryRelease notes
community.openvpn.netReleaseHistoryRelease notes

Changes to this CVE

Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).

11.08.2026Initial analysis by NVDNVD

Newly listed as affected:

OpenVPN (2.6.0 – before 2.6.20; 2.7 – before 2.7.2)

CVSS V3.1: AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:H

New references:

Show 5 original changes

Individual changes of this event as published by NVD
Type	Action	Before	After
CVSS	added	—	AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:H
Product configuration	added	—	OR cpe:2.3:a:openvpn:openvpn::::::::* versions from (including) 2.6.0 up to (excluding) 2.6.20 cpe:2.3:a:openvpn:openvpn::::::::* versions from (including) 2.7 up to (excluding) 2.7.2
Reference type	added	—	OpenVPN Inc.: https://community.openvpn.net/ReleaseHistory#openvpn-2620-released-22-april-2026 Types: Release Notes
Reference type	added	—	OpenVPN Inc.: https://community.openvpn.net/ReleaseHistory#openvpn-272-released-22-april-2026 Types: Release Notes
Reference type	added	—	OpenVPN Inc.: https://community.openvpn.net/Security%20Announcements/CVE-2026-40215 Types: Vendor Advisory

Source identifier: nvd@nist.gov

08.06.2026Receivedopenvpn.net

CVSS V4.0: AV:N/AC:H/AT:N/PR:L/UI:N/VC:H/VI:N/VA:H/SC:L/SI:N/SA:L

Weakness type: CWE-125, CWE-416

Description added or changed

New references:

Show 7 original changes

Individual changes of this event as published by NVD
Type	Action	Before	After
Description	added	—	A race condition in OpenVPN 2.6.0 through 2.6.19 and 2.7_alpha1 through 2.7.1 allows remote attackers to potentially cause a server crash or leak heap memory via a use-after-free triggered during TLS session promotion.
CVSS	added	—	AV:N/AC:H/AT:N/PR:L/UI:N/VC:H/VI:N/VA:H/SC:L/SI:N/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Weakness type (CWE)	added	—	CWE-125
Weakness type (CWE)	added	—	CWE-416
Reference	added	—	https://community.openvpn.net/ReleaseHistory#openvpn-2620-released-22-april-2026
Reference	added	—	https://community.openvpn.net/ReleaseHistory#openvpn-272-released-22-april-2026
Reference	added	—	https://community.openvpn.net/Security%20Announcements/CVE-2026-40215

Source identifier: security@openvpn.net

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