# CVE-2026-88964: OpenVPN integer underflow in domain search options

Source: https://junglewise.ai/threats/cve-2026-88964-an-integer-underflow-in-openvpn-version-2-7-alpha3-through-2-7-7  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-13. Updated: 2026-10-16  
License: CC BY 4.0 with a link back

CVE-2026-88964 · Severity: info · Published 2026-10-13

OpenVPN is a popular VPN client used to securely connect to remote networks. An integer underflow vulnerability in versions 2.7_alpha3 through 2.7.7 on Windows and Android allows a malicious VPN server to trigger a denial of service or leak sensitive information from the client's memory. An attacker operating a rogue VPN server could crash the client or extract data without the user's knowledge.

Technologies: [Openvpn](https://junglewise.ai/threats/technologies/openvpn). Vendors: [Openvpn](https://junglewise.ai/threats/vendors/openvpn).

## Quick answers

**Is CVE-2026-88964 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-88964 being exploited in the wild.

**How severe is CVE-2026-88964?** Informational severity, published 13 October 2026.

**Which products and versions are affected?** Openvpn 2.7_alpha3 through 2.7.7.

**Is there a fix for CVE-2026-88964?** Yes: fixed in 2.7.8. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-88964 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-88964?** Check whether you run Openvpn at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Fixed in 2.7.8

## Technical details

An integer underflow vulnerability exists in OpenVPN's handling of PUSH_UPDATE domain search options, affecting Windows and Android platforms in versions 2.7_alpha3 through 2.7.7. The vulnerability requires an authenticated remote server to send crafted packets, leading to out-of-bounds memory access. This results in either denial of service (application crash) or memory disclosure, with a fix available in version 2.7.8.

## Affected products

- OpenVPN OpenVPN 2.7_alpha3 through 2.7.7

## Timeline

- 2026-10-13: disclosed
- 2026-10-13: patched: Fixed in version 2.7.8

## References

- [https://community.openvpn.net/Security%20Announcements/CVE-2026-88964](https://community.openvpn.net/Security%20Announcements/CVE-2026-88964)

## Related threats

- [OpenVPN use-after-free in TLS session promotion or expiry](https://junglewise.ai/threats/cve-2026-84471-the-fix-for-was-incomplete-a-use-after-free-in-openvpn-2-6-0)
- [OpenVPN identity impersonation via embedded NUL in certificate subject](https://junglewise.ai/threats/cve-2026-84790-openvpn-2-7-alpha1-through-2-7-7-allows-remote-authenticated)
- [OpenVPN ACK packet retransmission denial of service](https://junglewise.ai/threats/cve-2026-84732-openvpn-ack-packet-retransmission-denial-of-service)
- [OpenVPN argument parsing vulnerability on Windows](https://junglewise.ai/threats/cve-2026-84256-openvpn-argument-parsing-vulnerability-on-windows)
- [OpenVPN binary planting on Windows](https://junglewise.ai/threats/cve-2026-84226-openvpn-binary-planting-on-windows)