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PatchSiren cyber security CVE debrief

CVE-2026-13122 Openvpn CVE debrief

CVE-2026-13122 is a denial-of-service vulnerability in OpenVPN versions 2.6.0 through 2.6.20 and 2.7_alpha1 through 2.7.4. The vulnerability allows remote attackers to trigger a reachable assertion when external-auth is enabled via a malformed authentication token. This issue can cause a denial of service, potentially disrupting VPN services. Users of affected OpenVPN versions should apply patches or mitigations to prevent potential denial-of-service attacks. The vulnerability has a CVSS score of 5.9 and a severity of MEDIUM.

Vendor
Openvpn
Product
Unknown
CVSS
MEDIUM 5.9
CISA KEV
Not listed in stored evidence
Original CVE published
2026-07-06
Original CVE updated
2026-07-09
Advisory published
2026-07-06
Advisory updated
2026-07-09

Who should care

Users of OpenVPN versions 2.6.0 through 2.6.20 and 2.7_alpha1 through 2.7.4 should apply patches or mitigations to prevent potential denial-of-service attacks. This includes OpenVPN administrators, security teams, and operators responsible for maintaining VPN services. Additionally, security teams should review the vulnerability's impact on their organization's security posture and implement compensating controls if necessary.

Technical summary

The vulnerability exists in OpenVPN's handling of authentication tokens when the external-auth option is enabled. A remote attacker can cause a denial of service by providing a malformed authentication token, which triggers a reachable assertion. This issue affects OpenVPN community versions 2.6.0 through 2.6.20 and 2.7_alpha1 through 2.7.4. The vulnerability has a CVSS score of 5.9, indicating a moderate severity level.

Defensive priority

Medium

Recommended defensive actions

  • Apply the official patches or updates provided by OpenVPN
  • Restrict access to OpenVPN services to trusted sources
  • Monitor OpenVPN logs for potential exploitation attempts
  • Consider implementing additional authentication mechanisms
  • Review compensating controls for exposed systems while remediation is scheduled and verified

Evidence notes

The CVE record was published on 2026-07-06T16:16:28.677Z and was last modified on 2026-07-09T13:06:19.040Z. The NVD entry is currently Analyzed. This information is based on the NVD entry and the CVE record. The vulnerability affects OpenVPN versions 2.6.0 through 2.6.20 and 2.7_alpha1 through 2.7.4. The external-auth option is a key factor in the vulnerability. Defenders should verify the affected scope and apply patches or mitigations accordingly.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-13122 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-13122

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

  • CVE-2026-13122 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-13122

    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.