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PatchSiren cyber security CVE debrief

CVE-2026-88964 OpenVPN CVE debrief

An integer underflow in OpenVPN versions 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. This vulnerability affects OpenVPN installations on Windows and Android platforms, particularly those using versions 2.7_alpha3 through 2.7.7. Defenders should assess exposure and prioritize verification and updates to prevent potential attacks. The vulnerability has a CVSS score of 7.1 and is considered HIGH severity.

Vendor
OpenVPN
Product
Unknown
CVSS
HIGH 7.1
CISA KEV
Not listed in stored evidence
Original CVE published
2026-10-13
Original CVE updated
2026-10-14
Advisory published
2026-10-13
Advisory updated
2026-10-14

Who should care

Defenders responsible for OpenVPN installations, particularly those using versions 2.7_alpha3 through 2.7.7 on Windows and Android, should assess exposure and prioritize verification and updates.

Why it matters

The integer underflow vulnerability in OpenVPN versions 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. Defenders should prioritize verifying and updating OpenVPN installations to prevent potential attacks.

  • Potential denial of service attacks against OpenVPN clients
  • Potential memory disclosure attacks against OpenVPN clients
  • Verification of OpenVPN installations and updates to prevent exploitation
  • Monitoring of OpenVPN logs for potential attacks

Technical summary

The integer underflow vulnerability in OpenVPN versions 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 vulnerability is caused by an integer underflow in the OpenVPN software, which can be exploited by remote authenticated servers to cause a denial of service or memory disclosure. Defenders should prioritize verifying and updating OpenVPN installations to prevent potential denial of service or memory disclosure attacks.

Defensive priority

Defenders should prioritize verifying and updating OpenVPN installations to prevent potential denial of service or memory disclosure attacks.

Recommended defensive actions

  • Verify OpenVPN installations and update to a fixed version if necessary
  • Monitor OpenVPN logs for potential denial of service or memory disclosure attempts
  • Implement additional security measures to prevent crafted domain search options from being sent to OpenVPN clients

Evidence notes

The CVE record and source item provide details on the integer underflow vulnerability in OpenVPN versions 2.7_alpha3 through 2.7.7 on Windows and Android.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-88964 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-88964

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-88964 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-88964

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

  • CVE-2026-88964

    Unverified legacy reference

    URL: https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/88xxx/CVE-2026-88964.json

    cve_program_cvelist_v5

  • Source reference

    Unverified legacy reference

    URL: https://community.openvpn.net/Security%20Announcements/CVE-2026-88964

    Supplemental source - vendor-advisory

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.