CVE-2026-88964Network attack vectorHinoki check available

Client crash or disclosure via domain-search underflow

Published Oct 13, 2026 · Updated Oct 13, 2026

Integer underflow in OpenVPN 2.7_alpha3 through 2.7.7 allows remote authenticated users to crash clients via domain search updates. In options.c, remove_option() and update_option() decrement domain_search_list_len past zero while clearing the list, leaving a wrapped index that causes subsequent resets to write outside the array. Windows and Android clients must accept PUSH_UPDATE messages from an authenticated malicious server; the documented consequences are client denial of service or memory disclosure, not established code execution.

CVSS severity6.5
Medium
EPSS probability0.47%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Integer underflow in OpenVPN 2.7_alpha3 through 2.7.7 allows remote authenticated users to crash clients via domain search updates. In options.c, remove_option() and update_option() decrement domain_search_list_len past zero while clearing the list, leaving a wrapped index that causes subsequent resets to write outside the array. Windows and Android clients must accept PUSH_UPDATE messages from an authenticated malicious server; the documented consequences are client denial of service or memory disclosure, not established code execution.

The record

CVE
CVE-2026-88964
Published
Oct 13, 2026
Updated
Oct 13, 2026
Vendor
OpenVPN Technologies, Inc.
Product
OpenVPN
Classifications
T1499
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Oct 13, 2026CVE publishedPublication date reported by the CVE source.
  2. Oct 13, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2.7_alpha3 <=2.7.7

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

OpenVPN Technologies, Inc. · OpenVPNversion=2.7_alpha3 <=2.7.7

Published CVSS scores

9.8TenableCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
6.5Amazon LinuxCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H
9.8TenableCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.5TenableAV:N/AC:L/Au:N/C:P/I:P/A:P
9.0TenableCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:U/RC:C

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Activity data is delayed. The latest report is Sep 28, 2026.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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