OpenVPN up to 2.7.7 integer underflow

CVSS Meta Temp Score
CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.
Current Exploit Price (≈)
Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.
CTI Interest Score
Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
6.3$0-$5k0.00-

Summaryinfo

A vulnerability labeled as critical has been found in OpenVPN up to 2.7.7. This impacts an unknown function. Such manipulation leads to integer underflow. This vulnerability is documented as CVE-2026-88964. The attack can be executed remotely. There is not any exploit available.

Detailsinfo

A vulnerability was found in OpenVPN up to 2.7.7. It has been rated as critical. Affected by this issue is an unknown part. The manipulation with an unknown input leads to a integer underflow vulnerability. Using CWE to declare the problem leads to CWE-191. The product subtracts one value from another, such that the result is less than the minimum allowable integer value, which produces a value that is not equal to the correct result. Impacted is confidentiality, integrity, and availability. CVE summarizes:

An integer underflow in OpenVPN version 2.7_alpha3 through 2.7.7 on Windows and Android allows remote authenticated servers to cause a denial of service or memory disclosure via crafted domain search options

The advisory is available at community.openvpn.net. This vulnerability is handled as CVE-2026-88964 since 09/10/2026. The exploitation is known to be easy. The attack may be launched remotely. The technical details are unknown and an exploit is not available. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 10/14/2026).

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Type

Name

Version

License

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA CVSS-B Score: 🔒
CNA CVSS-BT Score: 🔒
CNA Vector: 🔒

CVSSv3info

VulDB Meta Base Score: 6.3
VulDB Meta Temp Score: 6.3

VulDB Base Score: 6.3
VulDB Temp Score: 6.3
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Integer underflow
CWE: CWE-191 / CWE-189
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: no mitigation known
Status: 🔍

0-Day Time: 🔒

Timelineinfo

09/10/2026 CVE reserved
10/13/2026 +33 days VulDB entry created
10/14/2026 +0 days Advisory disclosed
10/14/2026 +0 days VulDB entry last update

Sourcesinfo

Advisory: community.openvpn.net
Status: Confirmed

CVE: CVE-2026-88964 (🔒)
GCVE (CVE): GCVE-0-2026-88964
GCVE (VulDB): GCVE-100-418526

Entryinfo

Created: 10/14/2026 00:42
Changes: 10/14/2026 00:42 (63)
Complete: 🔍
Cache ID: 216::103

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