---
id: CVE-2026-78221
title: >-
  An incorrect buffer size calculation in the Windows Interactive Service in
  OpenVPN 2.7_alpha1 through 2.7.6 allows local authenticated users to cause
  memory corruption or disclose sensitive information via crafted NRPT inputs.
summary: >-
  An incorrect buffer size calculation in the Windows Interactive Service in
  OpenVPN 2.7_alpha1 through 2.7.6 allows local authenticated users to cause
  memory corruption or disclose sensitive information via crafted NRPT inputs.
severity: medium
cvss: 5.9
cvssVector: 'CVSS:4.0/AV:L/AC:H/AT:P/PR:L/UI:P/VC:H/VI:N/VA:H/SC:H/SI:N/SA:H'
cwe:
  - CWE-131
vendor: OpenVPN
product: OpenVPN
affected:
  - OpenVPN >= 2.7_alpha1 <= 2.7.6
published: '2026-09-07'
updated: '2026-09-08'
sourceUpdated: '2026-09-08T19:07:52.113'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-78221'
references:
  - url: 'https://community.openvpn.net/Security%20Announcements/CVE-2026-78221'
    label: security@openvpn.net
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-78221.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-78221'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-78221'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-78221'
tags:
  - nvd
  - cve.org
  - csaf
  - vex
  - red-hat
epss: 0.00116
epssPercentile: 0.01826
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-09-08T14:54:35.321806Z'
cvssSource: cna
scores:
  cna: 5.9
  vendor: 7.5
ingestedAt: '2026-09-08T15:33:26.975Z'
---

## Overview

An incorrect buffer size calculation in the Windows Interactive Service in OpenVPN 2.7_alpha1 through 2.7.6 allows local authenticated users to cause memory corruption or disclose sensitive information via crafted NRPT inputs.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Vendor advisories

- **Red Hat VEX** · updated 2026-09-07 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-78221.json)