---
title: "CVE-2026-88964: OpenVPN - Integer Underflow"
description: "OpenVPN 2.7_alpha3 through 2.7.7 on Windows and Android contains an integer underflow caused by crafted domain search options, letting remote authenticated servers cause denial of service or memory disclosure."
url: https://panop.io/threat-heartbeat/CVE-2026-88964/
---

# CVE-2026-88964 OpenVPN - Integer Underflow

OpenVPN 2.7\_alpha3 through 2.7.7 on Windows and Android contains an integer underflow caused by crafted domain search options, letting remote authenticated servers cause denial of service or memory disclosure.

CVSS base score 7.1 /10

High

CISA KEV

Not listed

Public exploit

None known

Authentication

Required

EPSS

0.47% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-88964)

## Details

Type

Integer Underflow

Impact

Denial Of Service, Information Disclosure

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N/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

Published

13 October 2026

Updated

15 October 2026

Weakness

[CWE-125](https://cwe.mitre.org/data/definitions/125.html)

## Vendor fix

Update to the latest OpenVPN version beyond 2.7.7.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

## References

- [https://nvd.nist.gov/vuln/detail/CVE-2026-88964](https://nvd.nist.gov/vuln/detail/CVE-2026-88964)
- [https://community.openvpn.net/Security%20Announcements/CVE-2026-88964](https://community.openvpn.net/Security%20Announcements/CVE-2026-88964)

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## What this record can't tell you

- Whether you run the affected software, and where
- Whether an attacker can actually reach and exploit it
- The misconfigurations that never get a CVE number
- What it would cost the business, ranked into what to fix first

Panop answers these inside your environment, for this CVE and every other finding.

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