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OpenvpnApplication

CVE-2025-2704

HIGH · 7.5 CVSS v3.1 Published 2025-04-02
Fix available
A fix is available. Upgrade to after 2.6.13 or later.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
OpenVPN version 2.6.1 through 2.6.13 in server mode using TLS-crypt-v2 allows remote attackers to trigger a denial of service by corrupting and replaying network packets in the early handshake phase

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

OpenVPN versions 2.6.1 through 2.6.13 in server mode with TLS-crypt-v2 enabled are vulnerable to a denial of service attack. Remote attackers can corrupt and replay network packets during the early handshake phase, causing the VPN server to become unavailable.

MitigationUpgrade OpenVPN to version 2.6.14 or later. As a temporary workaround, consider disabling TLS-crypt-v2 if not required, or implement network-level rate limiting on the VPN port.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
OpenvpnApplication
Affected:>= 2.6.1, <= 2.6.13

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check OpenVPN version
    Run 'openvpn --version' or check via package manager (dpkg -l openvpn, rpm -qi openvpn)
    Affected if Version is 2.6.1 through 2.6.13 inclusive
  2. Identify if running in server mode
    Check configuration files in /etc/openvpn/server/ or /etc/openvpn/, or inspect running processes with 'ps aux | grep openvpn' to see if --server or --mode server flags are present
    Affected if OpenVPN is running as a server (not client)
  3. Verify TLS-crypt-v2 is enabled
    Search for 'tls-crypt-v2' in all .ovpn and .conf files under /etc/openvpn/ and the configuration directory
    Affected if TLS-crypt-v2 directive is present in any active server configuration file

You are affected if OpenVPN version is between 2.6.1 and 2.6.13, it is running as a server, and TLS-crypt-v2 is enabled in the configuration.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Upgrade available Upgrade to a release after 2.6.13
Interim mitigation

Upgrade OpenVPN to version 2.6.14 or later. As a temporary workaround, consider disabling TLS-crypt-v2 if not required, or implement network-level rate limiting on the VPN port.

Fix this in Openvpn Scoped from the published advisory
  • Consultation2.0 h
  • Implementation3.0 h
  • Testing3.0 h
  • Review / QA1.0 h
9.0 hours of engineering $1,570
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,512.

Scan for this in your stack

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-2704 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data