Openvpn Access ServerApplication · Openvpn
CVE-2025-3110
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 · uneditedOpenVPN Access Server 2.7.2 through 3.1.0 accepts bare line-feed sequences inside HTTP header values, allowing remote attackers to perform HTTP request smuggling when deployed behind a reverse proxy
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 confidenceOpenVPN Access Server versions 2.7.2 through 3.1.0 improperly handles HTTP header values containing bare line-feed (LF) characters. This allows attackers to inject arbitrary HTTP headers and perform request smuggling attacks when the server is deployed behind a reverse proxy, potentially bypassing security controls and accessing protected resources.
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
Openvpn Access ServerApplication
>= 2.7.2, <= 3.1.0CVSS 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
- High
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
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 checksWork through these to decide whether this CVE applies to you.
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Identify OpenVPN Access Server versionRun 'openvpn --version' or check the admin web interface login page footer for the version numberAffected if The installed version is between 2.7.2 and 3.1.0 inclusive
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Confirm reverse proxy deploymentExamine your network architecture documentation or inspect the web server configuration to determine if OpenVPN Access Server is behind a reverse proxy (nginx, Apache, HAProxy, cloud WAF, etc.)Affected if A reverse proxy is placed in front of the OpenVPN Access Server
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Check for direct server accessAttempt to access the OpenVPN Access Server directly on its direct IP/hostname (port 443/943) bypassing the reverse proxyAffected if The server is reachable both behind a reverse proxy AND directly on a separate endpoint
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Inspect HTTP header handlingSend a test HTTP request with a header containing a bare LF character (e.g., 'X-Test: value\nX-Injected: header') to the public endpoint and observe if both headers are processed by the backendAffected if Both the original and injected headers are processed, indicating vulnerability to header injection
You are affected if OpenVPN Access Server version is between 2.7.2 and 3.1.0 AND it is deployed behind a reverse proxy that forwards requests with bare LF characters in HTTP headers.
Generated from the published advisory. Verify against your own configuration.
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 dataUpgrade OpenVPN Access Server to version 3.1.1 or later. If immediate upgrading is not feasible, configure the reverse proxy to reject requests containing bare LF characters in HTTP headers.
Fix this in Openvpn Access Server
Scoped from the published advisory
- Consultation2.0 h
- Implementation3.0 h
- Testing2.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,272.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2025-3110 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2025-3110 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
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