CVE-2025-3110: OpenVPN Access Server 2.7.2 through 3.1.0 accepts bare line-feed sequences inside HTTP header values, allowing

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HIGH 7.5REMOTEUPGRADE

CVE-2025-3110 is a high-severity flaw (CVSS 7.5) affecting openvpn access server. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

OpenVPN 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

Why this priority

High severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.4% (top 62%)
CISA exploited list	No
Weakness	CWE-444
Published	2026-07-08
Last modified	2026-09-29

Publisher (CNA): OpenVPN Inc. · Vendor: openvpn

Last updated 2026-09-29 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-07-08 17:17 UTCPublished CVE record published
2026-09-29 19:10 UTCUpdated Record last modified

openvpn openvpn access server UPGRADE

Affected: >= 2.7.2 and <= 3.1.0

Fixed in: newer than 3.1.0

Safe to downgrade to: a release before 2.7.2

1. Check installed version

apt-cache policy openvpn-access-server || rpm -q openvpn-access-server || openvpn-access-server --version

2. UPGRADE to newer than 3.1.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade openvpn-access-server

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade openvpn-access-server

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 2.7.2 (Debian / Ubuntu)

apt-cache madison openvpn-access-server sudo apt install openvpn-access-server=<VERSION_BEFORE_2.7.2> sudo apt-mark hold openvpn-access-server

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list openvpn-access-server sudo dnf downgrade openvpn-access-server-<VERSION_BEFORE_2.7.2> sudo dnf versionlock add openvpn-access-server

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2025-3110?

openvpn access server: upgrade to newer than 3.1.0. Exact commands for each OS are on this page.

Is CVE-2025-3110 being exploited?

CVE-2025-3110 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2025-3110 affect?

CVE-2025-3110 affects openvpn access server. Severity is high (CVSS 7.5). OpenVPN 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

How urgent is CVE-2025-3110?

Priority 41/100. High severity; Remotely exploitable, no login, no user action

Software pages

OpenVPN vulnerabilities

References

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