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PatchSiren cyber security CVE debrief

CVE-2026-11604 OpenVPN CVE debrief

CVE-2026-11604 is a medium-severity vulnerability in OpenVPN ovpn-dco-win versions 2.0.0 through 2.8.3. An incorrect buffer size calculation in the epoch key generator allows a remote authenticated peer to trigger a heap-based buffer overflow and kernel memory corruption via a crafted data packet, resulting in a system crash (denial of service). The CVSS score for this vulnerability is 5.6, indicating a medium severity level.

Vendor
OpenVPN
Product
ovpn-dco-win
CVSS
MEDIUM 5.6
CISA KEV
Not listed in stored evidence
Original CVE published
2026-06-10
Original CVE updated
2026-08-11
Advisory published
2026-06-10
Advisory updated
2026-08-11

Who should care

Users of OpenVPN ovpn-dco-win versions 2.0.0 through 2.8.3 should be aware of this vulnerability and take steps to mitigate it.

Technical summary

The vulnerability is caused by an incorrect buffer size calculation in the epoch key generator of OpenVPN ovpn-dco-win. This allows a remote authenticated peer to send a crafted data packet that triggers a heap-based buffer overflow and kernel memory corruption, leading to a system crash.

Defensive priority

Medium

Recommended defensive actions

  • Update to a version of OpenVPN ovpn-dco-win that is not vulnerable.
  • Restrict access to the OpenVPN ovpn-dco-win service to only trusted peers.

Evidence notes

The CVE was published on 2026-06-10T22:16:55.643Z and last modified on 2026-06-11T15:21:30.653Z. The vendor is listed as Unknown Vendor, but evidence suggests the product is OpenVPN.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-11604 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-11604

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

  • CVE-2026-11604 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-11604

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

Supplemental references

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.