CVE-2020-15078Network attack vector

Authentication bypass via premature PUSH_REPLY

Published Apr 26, 2021 · Updated Aug 4, 2024

Authentication bypass in OpenVPN 2.5.1 and earlier allows remote attackers to receive control-channel data from deferred-auth servers. During a renegotiated session, the authentication-state logic can send PUSH_REPLY before AUTH_FAILED, exposing pushed options and a generated authentication token. Exploitation requires plugin- or management-based deferred authentication; token-enabled configurations can turn the disclosure into VPN access.

CVSS severity7.5
High
EPSS probability4.91%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in OpenVPN 2.5.1 and earlier allows remote attackers to receive control-channel data from deferred-auth servers. During a renegotiated session, the authentication-state logic can send PUSH_REPLY before AUTH_FAILED, exposing pushed options and a generated authentication token. Exploitation requires plugin- or management-based deferred authentication; token-enabled configurations can turn the disclosure into VPN access.

The record

CVE
CVE-2020-15078
Published
Apr 26, 2021
Updated
Aug 4, 2024
Vendor
OpenVPN Inc.
Product
OpenVPN
Classifications
CWE-305, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 26, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record 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=2.5.1 and earlier versions

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

OpenVPN Inc. · OpenVPNversion=2.5.1 and earlier versions

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

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.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-305Authentication Bypass by Primary Weakness
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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